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Before you Read
Q.1What does the title of the poem suggests to you? What do you think the poem is about?

ANSWER:
The title of the poem suggests the importance of silence.
The poem is about the importance of self-examination and introspection. It is also an appeal for universal harmony.

Think it Out
Q.1 What will counting up to twelve and keeping still help us achieve?

ANSWER:
Keeping still for this brief interval of time gives us a momentary pause to introspect and review the course of action. It is generally observed that most of the ills and troubles of the world are caused by our rush or hurry. Violence is caused by anger. Keeping quiet and still will give us necessary respite and ensure peace.

Q.2 Do you think the poet advocates total inactivity and death?

ANSWER:
No, he doesn’t advocate either total inactivity or death. He makes it quite clear that ‘stillness’ should not be confused with ‘total inactivity’ or equated to it. Total inactivity brings death. But Neruda has ‘no truck with death’. His stillness means halting of harmful and hostile human activities.

Q.3What is the ‘sadness’ that the poet refers to in the poem?

ANSWER:
The poet refers to the ‘sadness’ of failing to understand oneself in the monotonous every day existence. He also finds it sad that the humanity is moving towards its own ruin owing to its unanalyzed actions. He regrets the rush of outdoing others that has made us forget the values of humanity.

Q.4 What symbol from Nature does the poet invoke to say that there can be life under apparent stillness?

ANSWER:
The poet uses the symbol of the earth to illustrate the point that there can be life under apparent stillness.

SHORT ANSWER TYPE QUESTIONS (Word Limit: 30-40 words)
Q1. Why does Pablo Neruda urge us to keep still?
ANSWER:  Stillness is essential for calm reflection and quiet introspection. We hear the voice of conscience in moments of silence. The poet is convinced that most of human ills and miseries are caused by man’s hurry and rush to do things. The poet wishes that we may withdraw ourselves from our undesirable actions and keep still for a moment.

Q2. Why shouldn’t we “speak in any language” and “not move our arms so much”?
ANSWER: People of the world speak in different languages. They indulge in unnecessary debates and disputes. Most of these arguments lead to destructive wars. The poet urges people to stop speaking in any language. They must speak through their hearts. So far men have moved their arms only to harm others. Therefore, the poet wants that they should not move their arms so much. Let these arms rest for once. Let a feeling of mutual understanding , be created among human beings.

Q3. Pablo Neruda says:“we would all be together in a sudden strangeness.”
When can we experience such a moment? Why will that be an exotic moment?
ANSWER: Non-stop activity, unnecessary rush and noise have made our lives unpleasant and full of misery, pain and troubles. We must stop rushing, hurrying, worrying and running. Even the noise of engines and machines must stop for once. Then all of us will enjoy the sudden strangeness of that moment. It will be a unique moment. In that exotic or fascinating moment we shall feel totally relaxed, physically as well as mentally.

Q4. What does the poet ask the fisherman and the man collecting salt to dot What docs In-exactly want to convey by this?
ANSWER: Pablo Neruda is against any kind of violence. He addresses the fishermen and asks them not to harm whales living in the cold seas of the polar regions. He is also against any kind of self torturing. The man who is gathering salt has hint his hands. He asks this man to look after himself and take care of his injured hands.

Q5. What are the different kinds of war mentioned towards war?
ANSWER: The poet is against wars of all kinds. He wants a total stoppage of war. Green wars against the environment, wars with poisonous gases and wars with fire must be terminated (stopped) at once.

Q6. What alternative does Pablo Neruda suggest instead of indulging in wars?
ANSWER:  Instead of indulging in wars, the people must come out in their best dresses with then- brothers. They should go out for a walk under the shady trees and enjoy themselves doing nothing. This would bring the feeling of togetherness among them.

Q7. How does the poet distinguish ‘stillness’ from ‘total inactivity’? Why does Neruda saw I want no truck with death?
ANSWER:  Pablo Neruda is in favour of stillness or silence. We remain still and quiet for sometime. On the other hand, total inactivity is a permanent suspension of work. It is just like death. ‘Stillness’ should not be Confused with ‘total inactivity’. Life goes on as usual. There can’t be anything like total inactivity. The poet refuses to associate with death or deal with it.

Q8. Why does the poet fee! that we should not be so single-minded’?
ANSWER:  People are generally single-minded. They want to focus on only one thing. They want to keep their lives going. They are ever busy in their pursuit. The poet wishes that they would not be so much absorbed with always remaining on the move. They must have some respite or rest. They too need peace or silence.

Q9.Why do men become sad? How can this sadness be overcome?
ANSWER:  Men fail to understand themselves. They are always threatening themselves with death. When they realise their failure to understand themselves they become sad or helpless. Fear of death also makes them sad. Only a huge silence’ can interrupt this sadness. Such silence will do them good.

Q10. How might a huge silence interrupt the sadness of men?
ANSWER:  Men never understand themselves. Nor are they ever sure of their actions. They face another tragedy. Due to their own actions, they are threatening themselves with death. This realisation makes them helpless and sad. Only a huge (long) silence might interrupt this sadness and do them some good.

Q11. Under the apparent stillness there is life. Justify this statement giving an example from the poem ‘Keeping Quiet’.
ANSWER: Neruda does not equate stillness with total inactivity. He believes that under this apparent stillness there is life. We can learn it from the earth. When everything seems dead, the earth still remains alive. The earth is never dead. The life on the earth goes on as usual under the apparent stillness.

Q12. Justify the title ‘Keeping Quiet’.
ANSWER: The title of the poem is quite appropriate and logical. It suggests the necessity of quiet introspection. The people of the world are overactive and always on the move. Their activities have caused untold troubles and sufferings. Keeping quiet will do them a lot of good. It will save them from many harmful and violent activities. Moreover, it will help in reflecting over the fate of man and help in creating a feeling of mutual understanding among human beings.

Q13. Which is the exotic moment that the poet refers to in ‘Keeping Quiet’:[Delhi 201]
ANSWER: The poet talks about the exotic moment when everyone keeps quiet. There will be no rush for a second. The machines must stop for a moment. That moment will be fascinating for all of us. All of us shall enjoy the sudden strangeness of the moment together.

Before you Read
Q.1Have you ever visited or seen an elementary school in a slum? What does it look like?

ANSWER:

Yes, I have visited an elementary school in a slum. The school was in a pitiful state. Its dingy and neglected classrooms were devoid of even basic amenities like fan and lights. Every single window was broken and bore marks of rust. How the students in the classroom dealt with the outside noise or the winters was anybody’s guess. The ceilings too were full of cobwebs. The furniture was broken and almost unusable. The walls of the classrooms were as shabby, malnourished and disinterested as the students sitting in their enclosures. Even the teachers seemed to have lost their concern both for the students and their education. Moreover, I was shocked to know that the usage of toilets was restricted to the school staff.

Think it Out

Q.1What do you think is the colour of ‘sour cream’? Why do you think the poet has used this expression to describe the classroom walls?

ANSWER:
Sour cream indicates the colour cream or dirty white. The poet has used this expression to describe the poor dull and ill-equipped environment of the classroom. The walls were painted long ago by donations and since then no attention has been given to them. We see the neglect these children face. It adds to the dull ambiance.

Q.2The walls of the classroom are decorated with the pictures of ‘Shakespeare’, ‘buildings with domes’, ‘world maps’ and beautiful valleys. How do these contrast with the world of these children?

ANSWER:
All these totally contrast with the world of the children in the slum. They get half education, the value of education for the children is minimal and to have these pictures which are symbols of high quality education is incongruous here. The buildings with domes are examples of a civilised world, the world unknown to them. The world map is irrelevant to them because the slums, their world cannot be located by them. Finally, the beautiful valley with rivers and capes is meaningless to them. They just have the polluted sky to watch from the broken window panes. These children are deprived of natural beauty.

Q.3What does the poet want for the children of the slums? How can their lives be made to change?

ANSWER:
He wants the children of the slums to venture into the outside world, beyond the boundaries of their slums, and experience a better present and future life.
The elementary school in the slum does not serve any purpose with its poor infrastructure and disinterested students. The poet feels that the governor, inspector and visitors should take initiative to bring about a real change in their situation. To ensure a better way of living for them, they need to be given proper education and freedom from their present confines. They need opportunity, encouragement and optimism to be able to live life with purpose and zest.

SHORT ANSWER TYPE QUESTIONS :

Q1. In the opening stanza the imagery is that of despair and disease. Read the poem and underline the words /phrases that bring out these images.
ANSWER:  The following words/phrases bring out these images of despair and disease:
‘Rootless weeds’; ‘the air tom round their pallor’;
The tall girl with her weighed-down head’;
The paper-seeming boy, with rat’s eyes’.
‘The stunted, unlucky heir of twisted bones’.
‘gnarled disease’.

Q2. Why does Stephen Spender use the images of despair and disease in the first stanza of the poem and with what effect?
ANSWER:  He uses the images of despair and disease to describe the miserable and pathetic fives of the children living in slums. The faces of these children are pale and lifeless. They and their hair are like ‘rootless weeds’. The burden of fife makes them sit with their head ‘weighed down’. The stunted growth is depicted by ‘the paper-seeming bo/ and ‘the stunted unlucky heir of twisted bones’. Their weak bodies recite their fathers’ ‘gnarled disease’.

Q3. In spite of despair and disease pervading the lives of the slum children, they are not devoid of hope. Give an example of their hope or dream.
ANSWER:  The burden of poverty and disease crushes the bodies of these slum children but not their souls. They still have dreams. Even their foggy future has not crashed all their hopes. They dream of open seas, green fields and about the games that a squirrel plays in the tree room.

Q4. How does Stephen Spender picturise the condition of the slum children?
ANSWER:  Stephen Spender uses contrasting images in the poem to picturise the condition of the slum children. For example:
“A narrow street sealed in with a lead sky Far far from rivers, capes and stars of words.”
The first line presents the dark, narrow, cramped holes and lanes closed in by the bluish grey sky. The second fine presents a world of beauty, prosperity, progress, well-being and openness.

Q5. What is the theme of the poem ‘An Elementary School Classroom in a Slum’ ? How has it been presented?
ANSWER:  In this poem Stephen Spender deals with the theme of social injustice and class inequalities. He presents the theme by talking of two different and incompatible worlds. The world of the rich and the ‘civilized’ has nothing to do with the world of narrow lanes and cramped holes. The gap between these two worlds highlights social disparities and class inequalities.

Q6. What message does Stephen Spender convey through the poem An Elementary School Classroom in a. Slum’ ? What solution does he offer?
ANSWER:  Stephen Spender conveys the message of social justice and class equalities by presenting two contrasting and incompatible worlds. He provides a way out. For achieving any significant progress and development the gap between the two worlds must be abridged. This can be done only by breaking the barriers that bind the slum children in dark, narrow, cramped holes and lanes. Let them be made mentally and physically free to lead happy lives. Only then art, culture and literature will have relevance for them.

Q7. Who Ttrd, the ivor/d its world and ho,What does this world contain,?
ANSWER: The conquerors and dictators change the map of the world according to their whims and will. They change the boundaries of various nations and shape the ‘map’. Their fair map is of a beautiful world full of domes, bells and flowers, rivers, capes and stars.

Q8. Th e poet says. Aria yet. for these Children, these windows, not this map, their world’. Which world do these children belong to? Which world is irue ecssihlc to them?
ANSWER:  The world of stinking slums is the world that belongs to these poverty-stricken, ill-fed, under-nourished children. The narrow lanes and dark, cramped, holes or hovels make their world. The world of ‘domes’, ‘bells’ and ‘flowers’ meant for the rich is inaccessible to them. They can only dream of rivers, capes and stars.

Q9. Which images of the slums in the third stanza pr sent the picture of social disparity, injustice and class inequalities.
ANSWER:  The slum dwellers slyly turn in their ‘cramped holes’ from birth to death i.e. ‘from fog to endless nights’. Their surroundings are ‘slag heap’. Their children “wear skins peeped through by bones.’ Their spectacles are “like bottle bits on stones.” The image that sums up their harsh existence reads : “All of their time and space are foggy slum.”

Q10. So blot their maps with slums as big as do,in;” says Stephen Sp,.meter. What does the poet want to convex?
ANSWER:  The poet notices the creation of two different worlds—the dirty slums with their narrow lanes and cramped houses which are virtual hells. Then there are islands of prosperity and beauty where the rich and powerful dwell. The poet protests against the disparity between the lives of the people in these two worlds. He wants that the poor should enjoy social equality and justice. The fair ‘map’ of the world should have blots of slums as big as doom. The gap must be reduced between the two worlds.

Q11. Stephen Spender while writing about an elementary classroom hi a slum, questions the value of education in such a milieu, suggesting that maps of the world and good literature may raise hopes and aspirations, which win never be fulfilled. Yet the gown offers a solution/hope. What is it?
ANSWER:  The slum children are being imparted education in a room whose walls are off-white in colour but are decorated with the pictures of ‘Shakespeare’, ‘buildings with domes’, “world maps’ and ‘beautiful valleys’. The maps of the world and good literature may raise hopes and aspirations. They may try to steal slyly from their milieu but it is quite unlikely that their hopes and aspirations may be fulfilled. The only solution/hope for them is to break the artificial barriers that bind and cramp them. Once free from their milieu, they can enjoy beauty.

Q12. How can powerful persons viz. governor,inspector,visitor may contribute to improve the lot of slum children?
ANSWER:  Powerful persons like governors, inspectors and visitors may take an initiative and start abridging the gap between the worlds of the rich and poor. They can play an important and effective role in removing social injustice and class inequalities. They should break and dismantle all the barriers that bind these children and confine them to the ugly surroundings. They will have their physical and mental development only when they leave the filthy and ugly slums. All good things of life should be within their reach. They must enjoy the freedom of expression.

Q13. How far do you agree with the statement: “History is theirs whose language is the sun.”
ANSWER:  This metaphor contains a vital truth. This world does not listen to the ‘dumb and driven’ people. Only those who speak with confidence, power, authority and vision are heard and obeyed. Those who create history are people whose ideas and language can motivate, move, inspire and influence millions of people. In order to be effective, their language must have the warmth and power of the Sun.

Before You Read

Q.1Ageing is a natural process; have you ever thought what our elderly parents expect from us?

ANSWER:
Aged people usually undergo pangs of loneliness and need companionship. The pessimistic approach they develop towards life can be shunned only if we provide them with abundant love, care, importance and empathy. They expect their children to sit calmly and talk to them about the happenings of their lives and to take their suggestions for making significant decisions. Their lost vitality can thus be easily rejuvenated. This happiness will encourage them to live life enthusiastically.

Think it Out

Q.1Why are the young trees described as ‘sprinting’?

ANSWER:
The young trees are personified in the poem. They seem to be running in the opposite direction when seen through the window of the moving car. The movement is juxtaposed with the expression on the mother’s face i.e. ashen like a corpse. The movement of the children and the trees is in stark contrast with the stillness associated with the mother.

Q,2Why has the poet brought in the image of the merry children ‘spilling out of their homes’?

ANSWER:
The poet highlights the helplessness and frailty of old age with the help of contrasts. The mother dozes off mouth open, whereas the children spilling out of their homes signify movement and energy, enthusiasm and vivacity, which the old people are bereft off.

Q.3Why has the mother been compared to the ‘late winter’s moon’?

ANSWER:
The mother has been compared to the late winter’s moon which is dull and shrouded. It symbolizes the ebbing of life. The moon brings to the poets mind night or the approaching end of life. The mother like the late winter’s moon is dull, dim and dismal.

Q.4What do the parting words of the poet and her smile signify?

ANSWER:
The parting words ‘see you soon Amma’ are used by the poet to reassure the mother and to infuse optimism in the poet herself. The poet accepts the reality yet keeps up the façade of smiling in order to put up a brave front. It requires a lot of effort and hence the poet has used the poetic device of repetition.

Short Answer Type Question:

Q1. Where was the poet going and who was with her?
ANSWER: The poet was driving from her parent’s home to the Cochin airport. The poet’s mother had comfe to see her off. She was sitting beside her. She was dozing with her mouth open. The words ‘driving’ and ‘doze’ provide a contrast between images of dynamic activity and static passivity respectively.

Q2. What was the poet’s childhood fear? [All India 2014]
ANSWER:  The child is always in fear of being separated from his parents. In the same way, the poet’s fear as a child was that of losing her mother or her company.

Q3. What does the poet’s mother look like? What kind of images has the poet used to signify her ageing decay?
ANSWER: The poet’s mother is sixty-six years old. She is sitting beside the poet and dozing with her mouth open. This is a sign of old age. Usually old people keep their mouth open to overcome breathing problems. Her face looked pale and faded like ash. Actually, she is an image of death as her ‘ashen’ face looks like that of a corpse.

Q4. What does the poet realise with pain? Why does the poet ‘put that thought away’ and look outside?
ANSWER: The lifeless and faded face of the poet’s mother pains her heart. She looks lifeless like a corpse. She provides an image of passivity, decay and death. The old lady seems to be lost in her thoughts. The poet needs a distraction, a change. She puts that thought away and looks outside. There she gets a picture of life, happiness and activity.

Q5. Describe the world inside the car and compare it to the activities taking place outside?
ANSWER: The pale and faded face of the poet’s mother looks lifeless like a corpse. Her dozing with mouth wide open suggests passivity, decay and death. Outside the car, the poet watches young trees speeding past them. They seem to be running fast or sprinting. Happy children are moving out of their homes cheerfully. They present an image of life, dynamism and activity.

Q6. Why does the poet look outside? What does she see happening outside?
ANSWER: The thought of the ageing mother at sixty-six and her pale and ashen face looking like a corpse becomes too heavy for the poet to bear. She needs a distraction, a diversion and therefore she looks outside. She watches young trees. These trees speed past them and appear to be sprinting. Then she sees happy children moving out of their houses and making merry.

Q7. How has the poet contrasted the scene inside the car with the activities going on outside?
ANSWER: The poet has used beautiful images to highlight the stark contrast between the scene inside the car and the activities going on outside. The ‘ashen’ face of the poet’s mother is pale and lifeless. It looks like that of a corpse. She is dozing and lost to herself. The image of the ‘dozing’ mother is contrasted with the ‘spilling’ of children. The ‘ashen’ and ‘corpse¬like’ face is contrasted with the young trees sprinting outside.

Q8. What does the poet do after the security check-up? What does she notice?
ANSWER:  They have to pass through a security check-up at the airport. After it, the poet stands a few yards away. Before saying parting words to her mother, she looks at her mother again. Her face looks pale and colourless like the late winter’s moon. She presents a picture of ageing and decay.

Q9. Why is the poet’s mother compared to the late winter’s moon?
ANSWER:  The poet’s mother has been compared to the late winter’s moon to bring out the similarity of ageing and decay. The late winter moon looks hazy and obscure. It lacks shine and strength. The poet’s mother has an ‘ashen’ face resembling a corpse. She has lost her shine and strength of youth. The comparison reinforces the impact.

Q10. What is the poet’s familiar ache and why does it return?
ANSWER: The poet is pained at the ageing and decaying of her mother. The fear is that with ageing comes decay and death. The sight of her old mother’s ‘ashen’ and corpse-like face arouses “that old familiar ache” in her heart. Her childhood fear returns. She is also pained and frightened by the idea that she may have to face all these things herself.

Q11. How does Kamala Das try to put away the thoughts of her ageing mother?[All India 2014]

  ANSWER: Kamala Das was in much trouble after seeing the lifeless and faded face of her mother. The old lady seemed to be lost in her own thoughts. The poetess turned away her attention from her mother and looked outside. The outside world was full of life and activity. The young trees seemed to be running fast. The children looked happy while moving out of their homes.

Q12. Why does the poet smile and what does she say while bidding good bye to her mother ?
OR
With fear and ache inside her heart and words of assurance on lips and smile on the face, the poet presents two opposite and contrasting experiences. Why does the poet put on a smile?
  ANSWER: The ‘wan’, ‘pale’, face of the poet’s mother at sixty-six brings an image of decay and death. It brings that old familiar fear of separation back. She fears the ultimate fate of human beings. But she has to put on a brave face. She regains self-control. She composes herself and tries to look normal. She utters the words of assurance that they will meet again soon. She tries to hide her ache and fear by smiling continuously.

Q13. What poetic devices have been used by Kamala Das in ‘My Mother at Sixty-six’?
  ANSWER:  The poem ‘My Mother at Sixty-six’ is rich in imagery. Kamala Das uses the devices of comparison and contrast. The use of simile is very effective. The face of the poet’s old mother is described as ‘ashen’. This ashen face is ‘like that of a corpse’. The poet uses another simile. The “wan, pale’ face of the mother is compared to ‘a late winter’s moon’.
The poem excels in contrasts. The old ‘dozing’ lady inside is contrasted with the young trees “sprinting” and merry children “spilling” out of their homes.

Think As you Read

Q.1Where was it most likely that the two girls would find work after school?

ANSWER:
The two girls, Sophie and Jansie, were already destined for a job in the biscuit factory and it was likely that they would work there after school.

Q.2What were the options that Sophie was dreaming of? Why does Jansie discourage her to have such dreams?

ANSWER:
Sophie dreamt of opening a boutique or becoming an actress or a fashion designer. She thought that she would be offered the position of a manager and that she would work there till the time she saves enough money for her boutique.
Keeping in mind their lower middle class family background, Jansie discourages Sophie to have such dreams. Jansie is more realistic and practical in life, and hence, knows that big ambitions cost heavy investments, something their working-class status could not afford.

Q.3Why did Sophie wriggle when Geoff told her father that she had met Danny Casey?

ANSWER:
Sophie knew her father well. He would be angry if he knew of her meeting with the young Irish footballer, Danny Casey. She didn’t tell him. When Geoff told his father about it, he became angry. He turned his head to look at her with disdain. Sophie wriggled where she was sitting at the table.
Q.4 Did Geoff believe what Sophie says about her meeting with Danny Casey?

ANSWER:
No, Geoff doesn’t believe what Sophie says about her meeting with Danny Casey. First, he looks round in disbelief and says, “It can’t be true”. Again he says, “I don’t believe it.” Sophie then narrates how Danny Casey came and stood beside her. Geoff asks her, “What does he look like?” So, he doesn’t seem to be convinced that Sophie met Danny Casey.

Q.5Does her father believe her story?

ANSWER:
Sophie’s father does not believe her story and he warns her that her “wild stories” might land her into trouble.

Q.6How does Sophie include her brother Geoff in her fantasy of future?

ANSWER:
Sophie was jealous of the fact that her brother had access to the world outside. She fantasises about going to these places with him some day in the future wearing a yellow dress. She fantasises that the world would rise to greet them.

Q.7Which country did Danny Casey play for?

ANSWER:
Danny Casey played football for Ireland.

Q.8 Why didn’t Sophie want Jansie to know about her story with Danny?

ANSWER:

Sophie didn’t want Jansie to know about her encounter with Danny because she feared that Jansie would spread her story to the whole neighbourhood.

Q.9Did Sophie really meet Danny Casey?
ANSWER:
Sophie did not meet Danny Casey in reality. She made up the story of her encounter with Danny Casey only to seek the attention her brother, Geoff.

Q.10 Which was the only occasion when she got to see Danny Casey in person?
ANSWER:
The only occasion when Sophie got to see Danny Casey in person was when the family went to watch United on Saturday. Sophie, her father and little Derek went down near the goal. Geoff went with his mates higher up. United won two-nil. Her idol Casey drove in the second goal. She saw the Irish genius going round two big defenders on the edge of penalty area. He beat the hesitant goal keeper from a dozen yards. Sophie glowed with pride.

Understanding the Text
Q.1 Sophie and Jansie were class-mates and friends. What were the differences between them that show up in the story?

ANSWER:
Sophie and Jansie were different from each other. Sophie was a dreamer who enjoyed creating her own fantasy world using her imagination. She showed an urge to transcend her working-class status and attain sophistication by pursuing the ambition of a fashion designer or an actress. Jansie, on the other hand, was more practical and realistic than Sophie. She tried to pull Sophie back to reality, but all in vain. Jansie’s sensibility and maturity are evident in her attempt to remind her friend that they were earmarked for the biscuit factory, and expensive dreams were inappropriate to their financial status.

Q.2How would you describe the character and temperament of Sophie’s father?

ANSWER:

Sophie’s father has a plumpy face looking grimy and sweaty. He doesn’t seem to be a soft or sophisticated man. Sophie fears his agressive manliness. He is a realist and does not believe in his daughter’s wild stories. He loves watching football. He hopes young Casey will be as good as Tom Finney. He wishes that the young footballer keeps away from all distractions. He shouts instructions to Casey at the playground. When the Irish genius , beats the hesitant goal keeper, Sophie’s father screams with joy and pride. He goes to a pub to celebrate the victory.

Q.3Why did Sophie like her brother Geoff more than any other person? From her perspective, what did he symbolise?

ANSWER:
Sophie liked her brother, Geoff, more than anybody else because he was not in the habit of talking much and remained lost in his own thoughts. She envied his silence and thought that he had access to an unknown world. She wanted to be a part of that world where she fancied herself wearing glamorous clothes and being welcomed by everyone. For Sophie, Geoff symbolised liberty from the monotonous and colourless life they had been living.

Q.4What socio-economic background did Sophie belong to? What are the indicators of her family’s financial status?

ANSWER:
Sophie belongs to a lower middle class socio-economic background. She lives in a small house with her parents and two brothers, Derek and Geoff. When she returns home after school, she feels choked with the steam of the stove and is disgusted with the dirty dishes piled in a corner. Her mother’s back has become stooped and bent by handling all the household chores and responsibilities on her own. Her father is a hard labourer and her elder brother, Geoff, works as an apprentice mechanic in a garage situated far away from his house. Her family wants Sophie to join work immediately after her school. These are some of the indicators of Sophie’s family’s financial status.
Talking about the Text
Discuss in pairs.

Q.1Sophie’s dreams and disappointments are all in her mind.

ANSWER:
Sophie was a dreamer who often made up stories for herself and for others. One possibility might be that she wanted to escape the squalor of daily life with the help of her fantasies. Her encounter with Danny Casey was a made-up story for the sake of catching her brother’s attention. Eventually, she gets so much engrossed in it that she starts to live the fantasy. When Danny Casey does not arrive for the second ‘date’, she experiences disappointment. However painful and disappointing her fantasy might be, she was not willing to accept reality. Her dreams and disappointments are figments of her
imagination.

Q.2It is natural for teenagers to have unrealistic dreams. What would you say are the benefits and disadvantages of such fantasising?
ANSWER:
Teenage is the phase of life which constitutes of major changes in the life of an individual. During this phase, a person learns many things, sets his career goals, and deals with peer pressure and the pressure of adults’ expectations. Hence, it is natural for teenagers to fantasise and to have unrealistic dreams.

Advantages: Fantasising, based on realistic goals or the world around, provides a means to reach higher ambitions and dreams. Aspiring for higher career goals and working hard may ensure successful career prospects. Thus, it instills confidence and a spirit to achieve one’s desire. In difficult situations of life, it helps instill positivity and optimism. It is a talent in those known as creative.

Disadvantages: Fantasising builds a gap between fantasy and reality. The realisation of the disparity between one’s goals and capabilities may be painful. Non achievement may also lead to disappointment, depression or suicidal tendencies. Moreover, it is a sheer wastage of time for many.

Short Answer Type question:

Q1. What does Sophie dream of doing after she passes out of school? Why do you call it a ‘dream’ and not a ‘plan’?
  ANSWER: Sophie dreams to have a boutique of her own. It will be the most amazing shop the city has ever seen. She says that she will buy a boutique if ever she comes into money. She does not mind becoming an actress to run a boutique as a side business. Since she has no money or experience, it is called a ‘dream’ and not a ‘plan’.

Q2. What are the other dreams of Sophie in addition to having a boutique?
ANSWER:  The greatest dream of Sophie is to have a boutique. She wants to be a bit sophisticated and rise above her lower-middle class status. Her other dream is of being an actress as “there’s real money in that”. Moreover, actresses don’t work full time. She can look after her first love i.e. boutique as a side business. She has another option. She can be a fashion designer, and do something sophisticated.

Q3. Why does -Jansie say : “Soaf, you really should be sensible” ?
ANSWER: Jansie knows Sophie’s family background and financial position. She knows that both of them are earmarked for that biscuit factory. Sophie dreams of big and beautiful things like having a boutique or becoming an actress or a fashion designer. All these things need a lot of money and experience. Sophie has neither of them. So Jansie being down-to-earth advises her to be sensible and stop having wild dreams.

Q4. Compare and contrast Sophie and Jansie?
OR
Jansie is Sophie’s classmate and friend but doesn’t entertain any ‘wild dreams’like her. Why?
ANSWER:  Sophie and Jansie are classmates and friends, but the similarity ends here. They are poles ’ apart in thinking and temperament. Sophie is an incurable dreamer and escapist. She dreams of big and beautiful things, which are beyond her reach.
On the other hand, Jansie is realistic and practical. She knows that they are poor and will have to work in the biscuit factory after leaving school. She is well aware that big things require big money and experience, which they don’t have. It is better to live in reality and think accordingly.

Q5. What job is Geoff engaged in? How does he differ from his sister, Sophie?
ANSWER:  Geoff is a grown up boy. He left school three years ago. Now he is an apprentice mechanic. He has to travel to his work each day to the far side of the city. He speaks little but listens to his sister’s ‘wild stories’. But he is not a day dreamer like her. He knows the financial limitations of his family. He cautions Sophie against entertaining dreams for a celebrity like Danny Casey.

Q6. Why was Sophie jealous of Geoff’s silence?
ANSWER: Geoff was almost grown up now. He spoke little. Words had to be extracted out of him like stones out of the ground. Sophie was jealous of his silence. She knew that when he was not speaking, he was away somewhere. He was out in the surrounding country—in those places she had never been. She wanted to share her brother’s affection.

Q7. What does Sophie tell Geoff about her meeting with Danny Gasey? How does Geoff react to it?
ANSWER: Sophie tells Geoff that she met Danny Casey. Geoff is surprised. He looks round abruptly and asks ‘where?’ Sophie replies that she met him in the arcade. Geoff can’t believe her. He says, “It’s never true.” He asks her, “What does he look like?” She replies that he has green eyes and is not very tall. Geoff is still not convinced.

Q8. How does Sophie’s father react when Geoff tells him about her meeting with Danny Casey?
ANSWER: Geoff informs his father that Sophie had a meeting with Danny Casey. He turns his head on his thick neck to look at her in disbelief. His expression is one of disdain. He ignores the news and goes on to talk about Tom Finney. He hopes that Danny will he like Tom Finney one day. When Sophie says that Casey is going to buy a shop, he reacts sharply. “This is another of your wild stories.”

Q9. “He don’t believe you—though he’d like to.” Who says so, about whom and in what context?
ANSWER: Geoff says so to Sophie about their father. He reacted sharply to her account of meeting Danny Casey. Geoff said that she had met him in the arcade and then told him how it had been. Their father said aggressively that she was going to talk herself into a load of trouble. Sophie asked Geoff to confirm that it was true. It was then that Geoff uttered these remarks. *-

Q10. Why do you think, does Goeff tell Sophie the following?
(i)“Casey must have strings of girls.”
(ii)“As if he’d ever show up.”
ANSWER:  Geoff knows that Sophie is still very young and immature. She is crazy after Danny Casey, the Irish wonder-boy. He tries to convince Sophie that a celebrity like Casey must have a large number of girls running after him. She says that he doesn’t have any. He will give her autograph next week if she cares to meet him next week. Geoff is not convinced. He doubts if he would ever show up.

Q11.Who was Danny Casey? How did the members of Sophie’s family react towards him?
ANSWER:  Danny Casey was a young Irish football player. He played for the United. The Irish prodigy could easily dodge the defenders and score goals. Sophie’s father was a football fan. He admired old heroes like Tom Finney and young wonder boy Casey. Geoff had a large poster of United first team squad on his bed room wall. There were three coloured photographs of Casey in the row below it. Every Saturday they went to watch United play.

Q12. Why was the visit of Sophie’s father and his family to watch United ‘their weekly pilgrimage’ ?
ANSWER:  Sophie’s father was a keen footfall fan. He took great interest in the career of Danny Casey, the Irish prodigy. Geoff, too was interested in football. Sophie considered Danny Casey her personal hero. She always dreamt of him. Casey was playing for United. The family visited the stadium regularly to watch him. So the family’s visit was like a religious or holy weekly ritual—a pilgrimage.

Q13. Where did Sophie meet Casey and what transpired between them?
ANSWER:  Sophie met Danny Casey in the arcade. It was she who spoke first and asked if he was Casey. He looked surprised. He was certainly Danny Casey as he had the Irish accent. She had already heard him on television. She asked him for an autograph for little Derek. But neither of them had any paper or pen. Before going he promised to give his autograph if she cared to meet him next week.

Q14. What promise does Sophie want Geoff to make and why ?
OR
Why does Sophie say: “Promise you’ll tell no one” and “Promise, Geoff-Dad’d murder me.”
ANSWER:  Sophie wants to confide in Geoff what happened dining her meeting with Danny Casey. Before telling him the details, she wants him to promise that he would tell no one about her meeting and the next ‘date’. She is afraid of her father’s anger. She fears he would murder her. Geoff assures her that she is quite safe. Their father does not believe such wild stories.

Q15. Did Geoff keep his promise? How do you know?
‘ OR
Why did Sophie say “Damn that Geoff, this was a Geoff thing not a Jansie thing.”
ANSWER:  Sophie had told Geoff about her meeting with Danny Casey and asked him to promise that he would tell no one. It was a secret between the two—something special just between them. Geoff did not keep his promise. He told Jansie’s brother Frank about it. Sophie cursed Geoff, as it was his doing, not Jansie’s.

Q16. Why did Sophie not want Jansie to know anything about her meeting with Danny Casey?
ANSWER: Sophie knew that Jansie was ‘nosey’. She was very inquisitive by nature. She took special interest in knowing new things about others. Sophie did not trust Jansie as she could not keep a secret. She could spread the rumour in the whole neighbourhood.

Q17. How did Jansie react at Sophie’s story of her meeting with Danny Casey ? [Delhi 2014]
ANSWER:  Jansie was a classmate and friend of Sophie. She lived in the same neighbourhood. She knew Sophie quite well. She was also aware of Sophie’s habit of dreaming. On learning of her meeting with Danny Casey, her first reaction was of disbelief. “You never did”, exclaimed Jansie. But when Sophie told her about her request for autograph, Jansie softened a little and said, “Jesus, I wish Fd have been there.”

Q18. What did Sophie want to keep a secret from her father and why? How did Jansie react to this disclosure?
ANSWER:  Sophie told Jansie that she wanted to keep her meeting with Casey a secret. There would be a row if her father knew it. Jansie thought that he would be pleased. Sophie told Jansie what a misery her father was. Moreover, she did not want crowd of people asking him about Danny Casey and her. She feared that he would murder her. Her mother felt upset whenever there was a row. Jansie assured Sophie that she could trust her to keep the secret.

Q19. Why did Sophie choose to walk by the canal? What did she do there?
ANSWER:  Sophie walked by the canal along a sheltered path. It was far away from the noise and crowd of the city. It was a place where she had often played when she was a child. There was a wooden bench beneath a solitary elm tree. Lovers sometimes came there. That was the most suitable place where she could dream of her hero Danny Casey.

Q20. How did Sophie react as she kept sitting for hours, waiting for Danny Casey and imagining his coming?
ANSWER:  At first Sophie was optimistic. She imagined him coming out of the shadows. When time had elapsed, pangs of doubt stirred inside her. She became sad and despondent. Danny would not come there at all. She feared that people would laugh at the story of her meeting with Casey.

Q21. Sophie is a typical adolescen.t hero-worshipper who carries her fantasising too far. Comment.
ANSWER:  Sophie is a dreamer and an escapist. She is also a hero-worshipper. Danny Casey, the wonderful Irish football player was her hero. She indulged in wishful thinking and dreams of meeting him. Her imagined meeting gave her immense pleasure. But the pangs of not meeting him made her sad and despondent.

Q22. “Sophie’s dreams and disappointments are all in her mind.” Do you agree? Give reasons in support of your answer.
ANSWER: I fully agree with the observation. Sophie’s dreams and disappointments are all in her mind, she is a hero-worshipper. The Irish prodigy is her hero. She imagines her meeting with him. Her day-dreaming makes her sad and despondent. The idea that Casey will not come at all is quite painful to her. Thus, her dreams and disappointments are products of her mind only. They have nothing to do with reality. ‘

Q23. Why did Sophie long for her brother’s affection? [All India 2014]
ANSWER:  Geoff was not veiy talkative. He was an introvert. Sophie thought that Geoff had access to the world where she had not got even a chance to visit. She wanted to be the part of her brother’s world. That is why she longed for his affection.

Long Answer Type Question:

Q1. What impression do you form of Sophie on reading the story ‘Going Places’?
OR
Sophie has her own dreams and disappointments, but they are all her creations—the creations of her own mind. Justify the statement.
ANSWER: Sophie is a young school girl. She dreams of big and beautiful things. Some of these are beyond her reach or her means. Her ambitions have no relation with the harsh realities of life. She thinks of having a boutique. She wants to have the most amazing shop this city has ever seen. Then she entertains the idea of being an actress There’s real money in that.’ Actresses do not work full time. So she would nm the boutique as a side business. If need be, she can be a fashion designer. She doesn’t realise that her family is not rich enough and her dreams can’t be fulfilled.
Sophie develops a romantic fascination for Danny Casey. He is a young Irish football player and the hero of her dreams. She indulges in hero worship. She tells a story that she met Casey. Her father calls it another of her “wild stories”. Even Geoff does not believe her. He tries to caution her. Casey is a celebrity. Many girls run after him. But Sophie ignores him.
She is an incurable dreamer. She has seen Casey only once, but all the time she thinks of him. She sits alone and waits for his arrival. She becomes sad and despondent when Casey does not come. She suffers because of her dreams. These dreams and disappointments are all the creations of her mind.

Q2. Compare and contrast Sophie and Jansie highlighting their temperament and aspirations.
ANSWER:  Sophie and Jansie are class-fellows and friends. They belong to lower middle class families. Both of them are earmarked for biscuit factory. Jansie’s feet are firmly planted on the ground. But Sophie is totally blind to the harsh realities of life. She dreams of big and beautiful things. She wants to have a boutique. She thinks of becoming an actress as there is lot of money in this profession. If need be, she can also be a fashion designer. In short, she loves to be grand and sophisticated. All her dreams are beyond her reach and resources. Jansie advises her to be sensible, but she remains a romantic dreamer.
Sophie and Jansie differ in thinking and temperament. Sophie is lost in her dream world. She shares her secret with only one person. It is her elder brother Geoff. Jansie is ‘nose/. She takes interests in learning new things about others. She can spread the story in the whole neighbourhood. So, Sophie doesn’t want to share secrets with her.
Sophie is an incurable dreamer and escapist. She is a hero-worshipper. She adores the young Irish footballer Danny Casey. She develops a fascination for her. She becomes sad and helpless but she doesn’t become wiser. She remains a dreamer. Jansie is practical and realist. She has no such unrealistic dreams.

Q3. Describe the bond between Geoff and Sophie in spite of differences in their temperament and thinking.
ANSWER: Geoff was Sophie’s elder brother. He was three years out of school. He was an apprentice mechanic. He travelled to his work each day to the far side of the city. He was almost grown up now. He spoke very little. Sophie was jealous of Geoff’s silence. He was quiet
and didn’t make new Mends easily. He thought that Sophie was too young and immature. Geoff was mature enough to understand his limitations and those of his family. He never dreamt of big and beautiful things.
In spite of difference in their temperaments, there was a close bond between the two. Geoff was always the first to share Sophie’s secrets. He knew that Sophie’s story of meeting with Danny Casey was not true. Still he listened to her. Sophie confided in him. Her secret was something special just between them. It was not meant for nosey Jansie who would spread it in the whole neighbourhood. Geoff tried to persuade Sophie. He warned her that Danny Casey was a celebrity. He must have many girls like her running after him. Sophie told him that Casey would give her an autograph if she cared to meet him next week. Geoff did not believe “he’d ever show up.” Thus, he acted like an elder brother.
Geoff and Sophie share a common trait. It is their fascination for the Irish prodigy, Danny Casey. But they differ in their thinking. Like his father, Geoff wished Casey to be a great footballer one day. Sophie had romantic fascination for Casey. It was something else other than football.

Q4. Who was Danny Casey ? How was he adored by the family of Sophie, and specially by Sophie and her father ?
ANSWER:  Danny Casey was an Irish Prodigy. He was a wonderboy of football. He had won the hearts of his countless fans. He played for United. Sophie’s family was obsessed with the Irish genius. Sophie’s father compared young Danny Casey to another great football player Tom Finney. He wished that Casey might be that good someday. He knew there were a lot of distractions for a youngster in the game those days. He wished that Casey would keep his head on his shoulders. Geoff remarked that he was with the best team in the country. He hoped that Casey would prove even a better player than Tom Finney. Geoff considered him the best. His father thought that he was too young for the first team. The fact was that with his exceptional ability he was playing for the first eleven.
On Saturday, Sophie’s family made their weekly pilgrimage to the stadium to watch United play their match. They watched their hero Danny Casey in action. He was running, going round the two big defenders. Then he was on the edge of the penalty area. Sophie’s father was screaming for him to pass. They saw him beating the hesitant goal keeper from a dozen yards. He scored the second goal. United won two-nil. Sophie glowed with pride. Geoff was ecstatic. Someone wished he were an Englishman. Little Derek declared that Ireland would win the world cup. Their father went to the pub to celebrate.
Sophie adored Danny Casey. She had a romantic fascination for the Irish prodigy. Her young heart throbbed for her hero. She imagined Casey coming to her. She would sit under an elm tree, waiting for Casey and dreaming of him. She realised that he would not come. This made her sad and dejected. Sophie became a victim of her own dreams and disappointments.

Think As you Read
Q.1 What are some of the positive views on interviews?
ANSWER:
Interview, in the 130 years of its existence, has become an inherent part of journalism. It is a useful means of communication that is, at times, considered to be an art, serving as a source of truth. Denis Brian has stated that in today’s world we get to know “our contemporaries” through their interviews.

Q.2Why do most celebrity writers despise being interviewed?

ANSWER:

Celebrity writers believe that interviews unduly interfere in their private lives. They regard themselves as victims of interviews. They claim that the interview in some way ‘diminishes’ them, just like some ancient cultures believed that a portrait of a person takes away his soul. Certain celebrities like V.S Naipaul have claimed that interviews leave them wounded, while others like Rudyard Kipling have referred to it as a crime and an immoral act.

Q.3 What is the belief in some primitive cultures about being photographed?

ANSWER:
Some primitive cultures believed that photographing a person is no less than stealing his/her soul out of the body and rendering him incomplete and slighted.

Q.4 What do you understand by the expression “thumbprints on his windpipe”?

ANSWER:
The expression means having been strangulated. The interview is an assault on a person as it makes him/her so tense that he/she feels as good as being choked.

Q.5 Who, in today’s world, is our chief source of information about personalities?

ANSWER:
In modern times, the chief source of information on personalities is the interviewer who, through his power and influence, gathers information and provides us with the best possible information on the interviewees. He extracts everything significant through his questions for us.

Understanding the Text

Q.1Do you think Umberto Eco likes being interviewed? Give reasons for your opinion.

ANSWER:
Yes, Umberto Eco, in all possibilities, likes being interviewed. He felt just at ease with the interviewer and answered all the questions fully and patiently without showing any hurry. He stated his achievement in a very modest manner and explained his philosophical views and interest clearly. He let the interviewer enter the secret about his craft with a loud laugh. Also, he elaborated his approach which was unique. He was mannerly, warm and properly responsive as well.

Q.2 What was distinctive about Eco’s academic writing style?

ANSWER:
Umberto Eco’s academic writing style is quite distinctive. It has a certain playful and personal quality about it. It is a marked departure from a regular academic style, which is usually depersonalised and often dry and boring.

Q.3Did Umberto Eco consider himself a novelist first or an academic scholar?

ANSWER:
Umberto Eco considered himself an academic scholar first and a novelist later. He makes his preference clear by saying, “I consider myself a university professor who writes novels on Sundays”. On week days he attends academic conferences and does other scholarly, non-fictional work.

Q.4What is the reason for the huge success of the novel, The Name of the Rose?

ANSWER:
‘The Name of the Rose’ is different sort of noveL It is quite serious noveL It is a detective story at one leveL But it also probes into metaphysics theology and medieval history. The reasons for the success of the book, however, remain a mystery.

Talking about the Text

Discuss in pairs or small groups.

Q.1The medium you like best for an interview, print, radio, or television.

ANSWER:

The medium I like best for an interview is the television. It has both audio and visual effect. It presents the interviewer and interviewee before the audience in their true colours. Usually celebrities accuse the reporters of misquoting them or misreporting them in the print media or the radio. This is not possible when they are face-to-face on the television. Their lip movement and body movement while replying to probing questions are there for all to see. The recording of various expressions coming on the face of the interviewee and his/her gestures and words are the additional advantages that television holds over the print media or the radio. The print media has dull, dry words alongside a picture whereas the radio tries to create the atmosphere by skilful variation of the sound. Both expect a lot of attention from the reader/audience.

Q.2Every famous person has a right to his or her privacy. Interviewers sometimes embarrass celebrities with very personal questions.

ANSWER:
Interviewers want to present exculsive and intimate details about the famous person they are interviewing. Some interviewrs focus on the public life and achievements of the individual only. They try to be objective in their approach as well as assesment. However, there are others who want to make their interviews more spicy and usually cross the thin limit of privacy of the individual. In their zeal to present good copy they embrass the famous person with the personal questions. Sometimes impact of such questions on famous person reveals his/her aversion as well as irritation at the silliness of the person. If they shout, they are accused of being rude and proud and if they keep mum thy are labelled as arrogant. In my opinion privacy of an individual must be respected.

In This Post we are  providing Chapter-9 MECHANICAL PROPERTIES OF SOLID NCERT MOST IMPORTANT QUESTIONS for Class 11 PHYSICS which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON MECHANICAL PROPERTIES OF SOLID

Question 1.
What are the factors due to which three states of matter differ from one’s Other?

Answer:
Three states of-matter differ from each other due to the following two factors:
(a) The different magnitudes of tester atomic and intermolecular forces.
(b) The degree of random thermal motion of the atoms and molecules of a substance depends upon the temperature.

Question 2.
When we stretch a wire, we have to perform work Why? What happens to the energy given to the wire in this process?

Answer:
In a normal situation, the atoms of a solid are at the locations of minimum potential energy. When we stretch a wire, the work has to be done against interatomic forces. This work is stored in the wire in the form of elastic potential energy.

Question 3.
Why are the bridges declared unsafe after long use?

Answer:
A bridge during its use undergoes alternative strains a large number of times each day, depending upon the movement of vehicles on it. When a bridge is used for a long time it loses its elastic strength, due to which the number of strains in the bridge for given stress will become large and ultimately the bridge may collapse. Thus, !» to avoid this, the bridges are declared unsafe after long use..

Question 4 .
A heavy machine is to be installed in a factory. To absorb vibrations of the machine, a block of rubber is placed between the machinery and the floor. Which of the two rubbers (A) and (B) of Figure would you prefer to use for this purpose? Why?

Answer:
The area of this hysteresis loop measures the amount of heat energy dissipated by the material. Since the area of the loop B is more than that of A, therefore B can absorb more vibrations than that of Av Hence B is preferred.

Question 5.
Compare the densities of water at the surface and bottom of a lake 1oo m deep, given that the compressibility is 10322 per atm and 1 atm = 1.015 × 10⁵ Pa.
Answer:

Let V = Volume of 1 kg water at the surface.
V’ = Volume of 1 kg water at the bottom of lake 100 m deep
= V – ΔV, where ΔV = decrease in volume, increase in pressure, P = hρg = 100 × 10³ × 9.8 Nm²

If ρ_s and ρ_b be the densities of water at the surface and at the bottom of the lake respectively, then

Question 6.
A steel wire 2 mm in diameter is stretched between two clamps, when its temperature is 40° C. Calculate the tension in the wire, when its temperature falls to 30° C. Given, coefficient of linear
Answer:

If Δl be the change n length of the wire, then

Question 7.
When a weight W is hung from one end of a wire of length L (other end being fixed), the length of the wire increases by l fig. (a). If the wire is passed over a pulley and two weights W each is hung at the two ends fig. (b), what will be the total elongation in the wire?

Answer:
(a) Let Y = Young’s modulus of the material of the wire. If ‘a’ be its area of cross-section, then

(b) When the wire is passed over the pulley, let l’ be the increase in the length of each segment. Since L2 = length of each segment.

∴ Total increase in the length of the wire is given by
= l’ + l’ = 2l’ = 2 × l2 = l.

Question 8.
A uniform cylindrical wire is subjected to longitudinal tensile stress of 5 × 10⁷ Nm^-2. The Young’s Modulus of the material of the wire is 2 × 10¹¹ Nm^-2. The volume change in the wire is 0.02%. Calculate the fractional change in the radius of the wire.
Answer:

Question 9.
A wire loaded by the weight of density 7.6 g cm^-3 is found to measure 90 cm. On immersing the weight in water, the length decreases by 0.18 cm. Find the original length of the wire.

Answer:
Let L = original length of the wire =?
A = be its area of cross-section.
W = load attached to the wire.

Then Young’s Modulus of the wire is given by

Here, ΔL = 90 – L = Change in the length of wire.

Volume of weight attached,

∴ Mass of water displaced = V × density of water
= W7.6 × l = W7.6

∴ Net weight after immersing in water ¡s
W’ = W – W7.6 = 6.67.6 W

Length of wire after immersing ¡n water
= 90 – 0.18 = 89.82 cm.

∴ Increase in length on immersing in water,

Question 10.
Two exactly similar wires of steel and copper are stretched by equal forces. If the total elongation is 1 cm, find by how much each wire is elongated. Given Y for steel = 20 × 10¹¹ dyne cm^-2, Y for copper = 12 × 10¹¹ dyne cm^-2.

Answer:
Let Δl_s and Δl_c be the elongation produced in steel and copper wires respectively.
L_s, L_c be their respective lengths,
L_s = L_c (∵ wires are similar)
Y_s = 20 × 10¹¹ dyne cm^-2
Y_c = 12 × 10¹¹ dyne cm^-2
Δl_s + Δl_c = 1 cm
A = area of cross-section of each wire.
F = equal force applied.

∴ Using the relation,

Dividing (ii) by (i), we get

In This Post we are  providing Chapter-8 GRAVITATION NCERT MOST IMPORTANT QUESTIONS for Class 11 PHYSICS which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON GRAVITATION

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1.State two essential requisites of geostationary satellite?  

Ans.(1)The period of revolution of a satellite around the earth should be same as that of earth about its own axis (T=24hrs)

(2)The sense of rotation of satellite should be same as that of the earth about its own axis i.e. from west to east in anti-clockwise direction

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2.Show that an artificial satellite circling round the earth in an orbit of radius obeys keeper’s third low?

Ans.Orbital velocity of a satellite is

  = 

Where M is the crass of earth

Time period of satellite T = 

T = 

T = 

T²  = 

Thus  

Hence proved.

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3.A 400kg satellite in a circular orbit of radius 2 Re about the earth calculate the kinetic energy potential energy and total energy of the satellite?

R_E = 6.4×10⁶m

M = 6×10²⁴kg   

Ans.M = 6×10²⁴ kg M = 400 kg

R_E = 6.4×10⁶m

Hence r = 2R_E = 12.8×10⁶m

G = 6.67×10^-4 N m²/kg²

KE = 

P. E. = 

PE = -2 x 6.25 x 10⁹  = -12.5× 10⁹ Joules

T. E. = K. E + P. E

T. E. = 6.25 ×10⁹ – 12.50 × 10⁹

T. E. = 6.25 × 10⁹ Joules

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4. Answer the following:

(a) You can shield a charge from electrical forces by putting it inside a hollow conductor. Can you shield a body from the gravitational influence of nearby matter by putting it inside a hollow sphere or by some other means?

(b) An astronaut inside a small space ship orbiting around the earth cannot detect gravity. If the space station orbiting around the earth has a large size, can he hope to detect gravity?

(c) If you compare the gravitational force on the earth due to the sun to that due to the moon, you would find that the Sun’s pull is greater than the moon’s pull. (You can check this yourself using the data available in the succeeding exercises). However, the tidal effect of the moon’s pull is greater than the tidal effect of sun. Why?

Ans. (a) No (b) Yes

(a) Gravitational influence of matter on nearby objects cannot be screened by any means. This is because gravitational force unlike electrical forces is independent of the nature of the material medium. Also, it is independent of the status of other objects.

(b) If the size of the space station is large enough, then the astronaut will detect the change in Earth’s gravity (g).

(c) Tidal effect depends inversely upon the cube of the distance while, gravitational force depends inversely on the square of the distance. Since the distance between the Moon and the Earth is smaller than the distance between the Sun and the Earth, the tidal effect of the Moon’s pull is greater than the tidal effect of the Sun’s pull.

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5. Does the escape speed of a body from the earth depend on

(a) the mass of the body,

(b) the location from where it is projected,

(c) the direction of projection,

(d) the height of the location from where the body is launched?

Ans.

(a) No

(b) No

(c) No

(d) Yes

Escape velocity of a body from the Earth is given by the relation:

………………(i)

g = Acceleration due to gravity

R = Radius of the Earth

It is clear from equation (i) that escape velocity vesc is independent of the mass of the body and the direction of its projection. However, it depends on gravitational potential at the point from where the body is launched. Since this potential marginally depends on the height of the point, escape velocity also marginally depends on these factors.

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6. A comet orbits the Sun in a highly elliptical orbit. Does the comet have a constant (a) linear speed, (b) angular speed, (c) angular momentum, (d) kinetic energy, (e) potential energy, (f) total energy throughout its orbit? Neglect any mass loss of the comet when it comes very close to the Sun.

Ans.

(a) No

(b) No

(c) Yes

(d) No

(e) No

(f) Yes

Angular momentum and total energy at all points of the orbit of a comet moving in a highly elliptical orbit around the Sun are constant. Its linear speed, angular speed, kinetic, and potential energy varies from point to point in the orbit.

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7. As you have learnt in the text, a geostationary satellite orbits the earth at a height of nearly 36,000 km from the surface of the earth. What is the potential due to earth’s gravity at the site of this satellite? (Take the potential energy at infinity to be zero). Mass of the earth =  kg, radius = 6400 km.

Ans. Mass of the Earth, M =kg

Radius of the Earth, R = 6400 km =  m

Height of a geostationary satellite from the surface of the Earth,

h = 36000 km =  m

Gravitational potential energy due to Earth’s gravity at height h,

=

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8.Two uniform solid spheres of radii R and 2R are at rest with their surfaces just touching. Find the force of gravitational attraction between them if density of spheres be P?

Ans. Two spheres of density p and radii R and 2R

s = oo¹ = 2R+R=3R

F = 

F = 

F = 

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9.Find expressions for (1) potential energy (2) kinetic energy (3) total energy for an artificial satellite.

Ans.Potential energy of a satellite

U=  

U = GMm 

U = GMm 

U =GMm 

U = 

Kinetic energy KE = 

But 

K. E = 

 KE = 

Total energy of satellite E = 

E = – 

E = – 

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10.  Suppose there existed a planet that went around the sun twice as fast as the earth. What would be its orbital size as compared to that of the earth?

Ans. Lesser by a factor of 0.63

Time taken by the Earth to complete one revolution around the Sun,

= 1 year

Orbital radius of the Earth in its orbit, = 1 AU

Time taken by the planet to complete one revolution around the Sun, 

Orbital radius of the planet = 

From Kepler’s third law of planetary motion, we can write:

Hence, the orbital radius of the planet will be 0.63 times smaller than that of the Earth.

---

=

=

---

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In This Post we are  providing Chapter-7 SYSTEM OF PARTICLE AND ROTATIONAL MOTION NCERT MOST IMPORTANT QUESTIONS for Class 11 PHYSICS which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON SYSTEM OF PARTICLE AND ROTATIONAL MOTION

Question 1.
What is the difference between the centre of gravity and C.M.?

Answer:
C.G.: It is the point where the whole of the weight of the body is supposed to be concentrated i.e. on this point, the resultant of the gravitational force on all the particles of the body acts.
C.M.: It is the point where the whole of the mass of the body may be supposed to be concentrated to describe its motion as a particle.

Question 2.
There are two spheres of the same mass and radius, one is solid and the other is hollow. Which of them has a larger moment of inertia about its diameter?

Answer:
The hollow sphere shall have greater M.I., as its entire mass is concentrated at the boundary of the sphere which is at maximum distance from the axis.

Question 3.
What shall be the effect on the length of the day if the polar ice caps of Earth melt?

Answer:
Melting of polar ice caps will produce water spread around the Earth going farther away from the axis of rotation that will increase the radius of gyration and hence M.I. In order to conserve angular momentum, the angular velocity ω shall decrease. So the length of the day (T = 2πω) shall increase.

Question 4.
If only an external force can change the state of motion of the C.M. of a body, how does it happen that the internal force of brakes can bring a vehicle to rest?

Answer:
The internal force of brakes converts the rolling friction into sliding friction. When brakes are applied, wheels stop rotating. When they slide, the force of friction comes into play and stops the vehicle. It is an external force.

Question 5.
What do you understand by a rigid body?

Answer:
A rigid body is that in which the distance between all the constituting particles remains fixed under the influence of external force. A rigid body thus conserves its shape during its motion.

Question 6.
Distinguish between internal and external forces.
Answer:

1. The mutual forces between the particles of a system are called internal forces.
2. The forces exerted by some external source on the particles of the system are called external forces.

Question 7.
One end of a uniform rod of mass m and length L is supported by a frictionless hinge which can withstand a tension of 1.75mg. The rod is free to rotate in a vertical plane. To what maximum angle should the rod be rotated from the vertical position so that when left, the hinge does not break?

Answer:
Let θ = maximum angle = ?
T = 1.75 mg
When the rod is in a vertical position, then the net force acting on the rod
F= 1.75mg – mg = 0.75mg
when the rod rotates, centripetal force,


When the rod is in the displaced position A, then K.E. of rotation is converted in RE.
∴ P.E. of the rod at displaced position = mg h

For rod I = 13 mL²

∴ According to the law of conservation of energy,

Question 8.
A flexible chain of weight W hangs between two fixed points A and B at the same level as shown here.
Find (i) force applied by a chain on each endpoint.
(ii) the tension in the chain at the lowest point.

Answer:
Let W = weight of the chain
∴ w2 = reaction at each endpoint A and B vertically upward

w2 balances downward
(i) Component F sin 0 of force F applied by a chain on each point

(ii) At lowest point C, the tension T is horizontal and equals the horizontal component of force F

Question 9.
The moment of inertia of a body about a given axis is 1.2 kg m². Initially, the body is at rest. In order to produce a rotational K.E. of 1500J, for how much duration, an acceleration of 25 rads^-2 must be applied about that axis.
Answer:

Question 10.
A thin bar XY of negligible weight is suspended by strings R and S shown in fig. The bar carries masses of 10 kg and 5 kg. Find the tensions in the strings and the angle θ if the system is in the static equilibrium.

Answer:
T₁, T₂ = ?
θ = ?

Taking moments about point X, we get


Again taking moment about point Y, we get

Also for horizontal equilibrium

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In This Post we are  providing Chapter-6 WORK, ENERGY AND POWER NCERT MOST IMPORTANT QUESTIONS for Class 11 PHYSICS which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON WORK, ENERGY AND POWER

1. What is the speed of an aircraft if the pilot remains in contact with the seat, even while looping in vertical plane?

Ans. For the pilot to stay at rest, centripetal force should

be provided by his weight, i.e., mv2r=mg

∴v=rg

Q.2 The kinetic energy of a particle moving in a horizontal circle may remain the same everywhere. Is it true for the motion in a vertical circle.?

Ans. No. For the motion in a vertical circle, the speed of the particle at the bottom is 5gr and at the top is gr. Therefore, K.E. of the particle in a vertical circle is maximum at the bottom and minimum at the top.

Q.3 A stone of mass m tied to the ended of a string of length l is whirled in a vertical circle. What is the net force acting on the stone at the bottom and at the top of the vertical circle, if tension in the string at the bottom at the top is Tb and Tt respectively

?

Ans. Net force acting on the stone at the bottom of

the circle =Tb−mg

Net force at the top =Tt+mg

Q.4 Can magnitude of kinetic energy be negative?

Ans. No, kinetic energy can be zero or positive only

 because KE=12mv2, because m and v2 cannot 

be negative.

Q.5 What is the significant of negative mechanical energy?

Ans. Negative value of mechanical energy indicates a bound state electron in an atom and a satellite revolving around a planet both are in bound state having negative mechanical energy.

Q.6 If rain drop move decreasing acceleration, does work done by gravitational force on the drop change.

Ans. It should be clearly understood that whether the drop move with decreasing acceleration or with uniform speed work done by the gravitational force on the drop remains the same.

Q.7 Can a body have momentum without energy? Ans. Yes, when E=k+u=0 either both are zero or k=−u. thus K.E. may or may not be zero As P=2mk

∴P=0 only when k=0

and P≠0 when k=−u

Q.8 Can a body have momentum when its energy is negative?

Ans. Yes, when k<u, total energy E=k+u is negative, the body has the momentum (∵k≠0). For example in an atom, electron has momentum though its energy is negative.

Q.9 Can work be defined at a position or at instant?

Ans. No, work is not defined at a position or at an instant. Work is defined during the time interval within which the force has undergone displacement unlike velocity and acceleration, momentum and kinetic energy it is not the characteristic of moving body it is something which happen an a body which produces or destroys motion of the body.

Q.10 A man rowing boat upstream is at rest with respect to the shore is he doing work.

Ans. The boat is at rest with respect to the shore but itis moving up stream with respect to water. The man is doing work relative to the stream because he is applying force to produce relative motionbetween the boat and stream, but he does no work relative to the shore as displacement relative to shore is zero.

Q.11 Why a metal ball rebounds better than a rubber ball?

Ans. When rubber ball hits a massive object say earth the ball is distorted. A large amount of heat is generated in the ball by the rubbing of the rubber molecules against each other this effect is essentially absent in a band material so metal ball would often loseless energy upon collision than would a rubber ball.

Q.12 The outer casing of a rocket is burnt due to friction between casing and air, who supplies the energy necessary for burning. The rocket or the atmosphere?

Ans. Due to friction with the air the speed hence the kinetic energy of the rocket decreases. This decrease in the kinetic energy appears in the form of heat energy, thus energy necessary for burning is supplied by the rocket itself.

Q.13 An artificial satellite orbiting the earth in very thin atmosphere loses its energy gradually due to dissipation against atmospheric resistance- however small, why then does its speed increase progressively as it comes closer and closer to the earth.

Ans. As a satellite comes closer to the earth its potential energy decrease. According to the law of conservation of energy the total energy of the system must remain constant. Now total energy =KE+PE+ heat energy. Because the heat loss due to friction is very small a decrease in potential energy result in a net increase in kinetic energy. Hence speed of a satellite progressively increase as it comes closer to the earth.

Q.14 In a tug-of-war one team is slowly giving way to the other is work being done on the losing team. How about the wining team.

Ans. Work is done on the losing team because that team is being dragged in the direction of the force applied by the wining team. This work done is said to be positive work, work is also done on the wining team because the wining team is being displaced opposite to the direction of the force applied by the losing team. This work done is said to be negative work.

Q.15 In a circus, the diameter of globe of death is 30 m. From what minimum height must a cyclist start in order to roll down the inclined and go round the globe successfully?

Ans. Diameter of globe =30m

Radius of globe, r=15m

Let h be the minimum height from which the

cyclist after rolling down an incline will acquire velocity =2gh

For looping the loop, the minimum velocity at the lowest point should be 5gr.

∴5gr=2gh

⇒h=5r2=5×152=37.5m

In This Post we are  providing Chapter-5 LAWS OF MOTION NCERT MOST IMPORTANT QUESTIONS for Class 11 PHYSICS which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON LAWS OF MOTION

Question 1.
(a) State and prove impulse-momentum Theorem.

Answer:
It states that the impulse of force on a body is equal to the change in momentum of the body.
i.e. J = F_t = P₂ – P₁

Proof: From Newton’s Second law of motion, we know that

Let P₁ and P₂ be the linear momenta of the body at time t = 0 and t respectively.
∴ integrating equation (i) within these limits, we get


Hence proved.

(b) Prove that Newton’s Second law is the real law of motion.

Answer:
Proof: If we can show that Newton’s first and third laws are contained in the second law, then we can say that it is the real law of motion.
1. First law is contained in second law: According to Newton’s second law of motion,
F = ma …(i)
where m = mass of the body on which an external force F is applied and a = acceleration produced in it.

If F = 0, then from equation (1), we get
ma = 0, but as m ≠ 0
∴ a = 0

which means that there will be no acceleration in the body if no external force is applied. This shows that a body at rest will remain at rest and a body in uniform motion will continue to move along the same straight line in the absence of an external force. This is the statement of Newton’s first law of motion. Hence, the First law of motion is contained in the Second law of motion.

2. Third law is contained in second law: Consider an isolated system of two bodies A and B. Let them act and react internally.
Let FAB = force applied on body A by body B
and FBA = force applied on body B by body A

It \frac{\mathrm{d} \mathbf{p}_{\boldsymbol{A}}}{\mathrm{dt}} = rate of change of momentum of body A
and
\frac{\mathrm{d} \mathbf{p}_{\boldsymbol{B}}}{\mathrm{dt}} = rate of change of momentum of body B

Then according to Newton’s second law of motion,


(2) and (3) gives

As no external force acts on the system (∵ it is isolated), therefore according to Newton’s second law of motion,

or
Action = – Reaction,
which means that action and reaction are equal and opposite. It is the statement of Newton’s 3rd law of motion. Thus 3rd law is contained in the second law of motion.

As both First and Third Law is contained in Second law, so Second law is the real law of motion.

Question 2.
Derive the general expression for the velocity of a rocket in flight and obtain the expression for the thrust acting on it.

Answer:
The working of a rocket is based upon the principle of conservation of momentum. Consider the flight of the rocket in outer space where no external forces act on it.
Let m_o = initial mass of rocket with fuel.
V_u = initial velocity of the rocket,
m = mass of the rocket at any instant t.
v = velocity of the rocket at that instant.
d_m = mass of the gases ejected by the rocket, in a small-time it.
u =H velocity of exhaust gases,
DV = increase in the velocity of the rocket in a time dt.

∴ Change in the momentum of exhaust gases = dm. u
Change in momentum of rocket = – (m – dm) dv.

A negative sign shows that the rocket is moving in a direction opposite to the motion of exhaust gases.

Applying the law of conservation of linear momentum,
dm.u = – (m – dm) dv …(1)

As dm being very small as compared to m, so it can be neglected, Thus, eqn. (1) reduces to
dm.u = – m dv
or
dv = – u \frac{dm}{m} …(2)

Instantaneous velocity of the rocket:
At t = 0, mass of rocket = m0, velocity of rocket = v_o.
At t = t, mass of rocket = m, velocity of rocket = v.

∴ Integrating Eqn. (1) within these limits, we get

In actual practice, the velocity of exhaust gases nearly remains constant.

equation (3) gives the instantaneous velocity of the rocket. In general v_o = 0 at t = 0,

∴ Eqn. (3) reduces to

From Eqn. (4), we conclude that the velocity of the rocket at any instant depends upon:

1. speed (u) of the exhaust gases.
2. Log of the ratio of initial mass (m0) of the rocket to its mass (m) at that instant of time.

Upthrust on the rocket (F): It is the upward force exerted on the rocket by the expulsion of exhaust gases. It is obtained as follows:
Dividing Eqn. (2) by dt, we get


where F = ma is the instantaneous force (thrust).

From Eqn. (5), we conclude that the thrust (F) on the rocket at any instant is the product of the velocity of exhaust gases and the rate of combustion of fuel at that instant. Here negative sign shows that the thrust and velocity of exhaust gases are in opposite direction.

Question 3.
(a) Define inertia. What are its different types? Give examples.

Answer:
The tendency of bodies to remain in their state of rest or uniform motion along a straight line in the absence of an external force is called inertia.

Inertia is of the following three types:
1. The inertia of rest: When a body continues to lie at the same position with respect to its surrounding, it is said to possess inertia of rest. This situation may be changed only by the application of external force. For example, if a cot or sofa is lying in a particular place in the house, it will remain there even after days or years unless someone removes (by applying force) the same from its position. This is an example of the inertia of rest.

2. The inertia of motion: When a body is moved on a frictionless surface or a body is thrown in a vacuum, it will continue to move along its original path unless acted upon by an external force. In actual situations, air or floor etc. exert friction on the moving bodies so we are unable to visualize a force-free motion. This type of inertia when a body continues to move is called the inertia of direction.

3. In the above examples it is found that the direction of motion of the body or particle also does not change unless an external force acts on it. This tendency to preserve the direction of motion is called the inertia of direction.

(b) Explain Newton’s First law of motion. Why do we call it the law of inertia?
Answer:
According to the First law of motion, “Everybody continues to be in the state of rest or of uniform motion along a straight line until it is acted upon by an external force.”

It means that if a book lying on a table,-it will remain there for days or years together unless force is applied on it from outside to pick it.

Similarly, if a body is moving along a straight line with some speed, it will continue to do so until some external force is applied to it to change its direction of motion.

Thus First law tells us the following:

1. It tells us about the tendency of bodies to remain in the state of rest or of motion and the bodies by themselves can neither change the state of rest nor of uniform motion. This tendency is called inertia. To break the inertia of rest or motion or direction, we need an external force. Thus the definition of the first law matches with the definition of inertia and hence first law is called the law of inertia.
2. The first law of motion also provides the definition of another important physical quantity called force. Thus force is that agency which changes or tends to change the state of rest or of uniform motion of a body along a straight line.

(c) State Newton’s Second law of motion. How does it help to measure force? Also, state the units of force.
Answer:
It states that the time rate of change of momentum of a body is directly proportional to the force applied to it.

where a = \frac{dv}{dt} = acceleration produced in the body of mass m.
k = proportionality constant which depends on the system of units chosen to measure F, m, and a.

In the S.I. system, k = l,
∴ F = ma

The magnitude of the force is given by
F = ma …. (2)

Note: We have assumed that the magnitude of velocity is smaller and much less than the speed of light. Only under this condition Eqns. (1) and (2) hold good.

The definition of the Second law and its mathematical form is given in Eqn. (2) provide us a mean of measuring force.

One can easily find the change in velocity of a body in a certain interval of time. Both velocity and time can be easily measured. Thus by knowing the mass of the body one can determine both change in momentum as well as the acceleration of the body produced by an external force. If the force is increased, the rate of change of momentum is also found to increase. So also is the acceleration. Now with known values of m and we can find F.

Units of force: Force in S.I. units is measured in newton or N. From Eqn. (1) or (2) we can see that a newton of force is that fore? which produces 1 ms^-2 acceleration in the body of mass 1 kg.
1 newton = 1 kilogram × 1 metre/(second)²
or
1 N = 1 kg × 1 ms^-2 = 1 kg ms^-2

In CGS system force is measured in dyne
1 dyne = 1 gram × 1 cm/s2 = 1 g cm s^-2
Since 1 N = 1 kgm s^-2= 1000 g × 100 cm s^-2
= 10⁵ g cm s^-2 = 105 dyne
1 N = 10⁵ dyne
or
1 dyne = 10⁵ N

Gravitational Unit: If a falling mass of 1 kg is accelerated towards the Earth with 9.8 ms^-2, then the force generated is called 1 kg wt (1-kilogram weight) force. It is the S.I. gravitational unit of force.

We know that the earth accelerates the mass with g = 9.8 ms^-2
1 Kg wt = 9.8 N [1 kg × 9.8 ms 2 = 9.8 N]

C.G.S. gravitational unit is gf or g wt.
1 gf = 1g × 980 cms^-2
= 980 dyne

Question 4.
A hunter has a machine gun that can fire 50 g bullets with a velocity of 150 ms^-1. A 60 kg tiger springs at him with a velocity of 10 ms^-1. How many bullets must the hunter fire into the tiger so as to stop him in his track?

Answer:
m = mass of bullet = 50 gm = 0.050 kg
M = mass of tiger = 60 kg
v = velocity of bullet = 150 ms^-1
V = velocity of tiger = – 10 ms^-1
(∵ it is coming from opposite direction) .

Let n = no. of bullets fired per second at the tiger so as to stop it.
∴ p_i = 0 before firing …. (i)
p_f = n(mv) + MV …. (ii)

∴ According to the law of conservation of momentum,

Question 5.
A mass of 200 kg rests on a rough inclined plane of angle 300. If the coefficient of limiting friction is \frac{1}{\sqrt{3}} find the greatest and the least forces in newton, acting parallel to the plane to keep the mass ¡n equilibrium.

Answer:
Here, m = mass of body = 200 kg
Let angle of inclination = θ
μ_s = coefficient of limiting friction = \frac{1}{\sqrt{3}}

The rectangular components of mg are as shown in fig.

Here mg sin θ acts along the plane in the downward direction and is given by

(i) the least forces in newton, acting parallel to the plane to keep the mass in equilibrium. given by
f₂₁ =mg sinθ – F = 980 – 9800 = 0

(ii) The greatest force to be applied to keep the mass in equilibrium is given by
f₂ = mg sin θ + F = 980 + 980 = 1960 N.

Question 6.
Find the force required to move a train of 2000 quintals up an incline of 1 in 50, with an acceleration of 2 ms^-2, the force of friction being 0.5 newtons per quintal.

Answer:
Here, m = 2000 quintals
= 2000 × 100 kg (v 1 quintal = 100 kg)
sin θ = \frac{1}{50} , acceleration, a = 2 ms^-2

F = force of friction
= 0.5 N per quintal
= 0.5 × 2000 = 1000 N

In moving up an inclined plane, force required against gravity
= mg sin 0
= 2000 × 100 × 9.8 × \frac{1}{50}
= 39200N.
Also if f = force required to produce acce. = 2 ms^-2.
Then f = ma = 200000 × 2 = 400000 N

∴Total force required = F + mg sin θ + f
= 1000 + 39200 + 400000 = 440200 N.

Question 7.
A bullet of mass 0.01 kg is fired horizontally into a 4 kg wooden block at rest on a horizontal surface. The coefficient of kinetic friction between the block and the surface is 0.25. The bullet remains embedded in the block and the combination moves 20 m before coming to rest. With what speed did the bullet strike the block?

Answer:
Here, m₁ = mass of the bullet = 0.01 kg
m₂ = mass of the wooden block = 4 kg
μ₂ = coefficient of kinetic friction = 0.25
initial velocity ofblock, u₂ = 0, s = distance moved by combination=20 m

Let u₁ = initial velocity of the bullet
If v = velocity of the combination, then according to the principle of conservation of linear momentum,

If F = kinetic force of friction,
Then

Then retardation ‘a’ produced is given by

Question 8.
A force of 100 N gives a mass m₁ an acceleration of 10 ms^-2, and of 20 ms^-2 to a mass m₂. What acceleration would it give if both the masses are tied together?

Answer:
Let a = acceleration produced if m₁ and m₂ are tied together.
F = 100 N, Let a₁ and a₂ be the acceleration produced in m₁ and m₂ respectively.
∴ a₁ = 10 ms^-2, a₂ = 20 ms^-2 (given)

Question 9.
A balloon with mass M is descending down with an acceleration ‘a’ < g. What mass m of its contents must be removed so that it starts moving up with an acceleration ‘a’?

Answer:
Let F = retarding force acting on the balloon in the vertically upward direction.

When the balloon is descending down with an acceleration ‘a’, then the net force acting on the balloon in the downward direction is given
by
Ma = Mg – F
or
F = Mg – Ma ….(i)
When the mass m is taken out of the balloon, then its weight is
= (M – m)g

Now as the balloon is moving upward with acceleration ‘a’, so the net force acting on the balloon in the upward direction is given by:

Question 10.
Three blocks are connected as shown below and are on a horizontal frictionless table. They are pulled to right with a force F = 50 N. If m₁ = 5 kg, m₂ = 10 kg and m₃ = 15 kg, find tensions T₃ and T₂.

Answer:
Here, F = 50 N, m₁ = 5 kg, m₂ = 10 kg m₃ = 15 kg.

As the three blocks move with an acceleration ‘a’

To determine T₂: Consider the free body diagram (1). Here F and T2 act towards the right and left respectively.

As the motion is towards the right side, so according to Newton’s Second law of motion:

To determine T₃: Consider the free body diagram (2)