Chapter 10

Gravitation 

Exercises

1. How does the force of gravitation between two objects change when the distance between them is reduced to half?

āϝেāϤিāϝ়া āϏেāχāĻŦোā§°ā§° āĻŽাāϜ⧰ āĻĻূā§°āϤ্āĻŦ āφāϧাāϞৈ āĻš্ā§°াāϏ āĻšāϝ় āϤেāϤিāϝ়া āĻĻুāϟা āĻŦāϏ্āϤুā§° āĻŽাāϜ⧰ āĻŽাāϧ্āϝাāϕ⧰্āώāĻŖāĻļāĻ•্āϤি āĻ•েāύেāĻĻā§°ে āϏāϞāύি āĻšāϝ়?

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2. Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object?

āĻŽাāϧ্āϝাāϕ⧰্āώāĻŖāĻļāĻ•্āϤিāϝ়ে āϏāĻ•āϞো āĻŦāϏ্āϤুā§° āĻ“āĻĒā§°āϤ āϤেāĻ“ঁāϞোāϕ⧰ āĻ­ā§°ā§° āĻ…āύুāĻĒাāϤāϤ āĻ•াāĻŽ āϕ⧰ে। āϤেāύেāĻš'āϞে, āĻāϟা āĻ—āϧুā§° āĻŦāϏ্āϤু āĻĒাāϤāϞ āĻŦāϏ্āϤুāϤāĻ•ৈ āĻĻ্ā§°ুāϤāĻ—āϤিāϤ āύāĻĒā§°ে?

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3. What is the magnitude of the gravitational force between the earth and a 1 kg object on its surface? (Mass of the earth is 6 x 1024 kg and radius of the earth is 6.4 x 106 m.)

āĻĒৃāĻĨিā§ąী āφ⧰ু āχāϝ়াā§° āĻĒৃāώ্āĻ āϤ 1 āĻ•িāϞোāĻ—্ā§°াāĻŽ āĻŦāϏ্āϤুā§° āĻŽাāϜ⧰ āĻŽাāϧ্āϝাāϕ⧰্āώāĻŖ āĻļāĻ•্āϤিā§° āĻĒā§°িāĻŽাāĻŖ āĻ•িāĻŽাāύ? (āĻĒৃāĻĨিā§ąীā§° āĻ­ā§° āĻšৈāĻ›ে 6 āĻĻāĻļāĻ• 1024 āĻ•িāĻ—্ā§°া āφ⧰ু āĻĒৃāĻĨিā§ąীā§° āĻŦ্āϝাāϏাā§°্āϧ 6.4 āĻĻāĻļāĻ• 106 āĻŽি.)

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4. The earth and the moon are attracted to each other by gravitational force. Does the earth attract the moon with a force that is greater or smaller or the same as the force with which the moon attracts the earth? Why?

āĻĒৃāĻĨিā§ąী āφ⧰ু āϚāύ্āĻĻ্ā§° āĻŽāĻšাāϕ⧰্āώāĻŖāĻļāĻ•্āϤিā§° āĻĻ্āĻŦাā§°া āχāϜāύে āϏিāϜāύ⧰ āĻĒ্ā§°āϤি āφāϕ⧰্āώিāϤ āĻšāϝ়। āĻĒৃāĻĨিā§ąীāϝ়ে āϚāύ্āĻĻ্ā§°āĻ• āĻāύে āĻāĻ• āĻļāĻ•্āϤিā§°ে āφāϕ⧰্āώিāϤ āϕ⧰ে āύেāĻ•ি āϝিāϟো āĻĄাāϙ⧰ āĻŦা āϏ⧰ু āĻŦা āϚāύ্āĻĻ্ā§°āχ āĻĒৃāĻĨিā§ąীāĻ• āφāϕ⧰্āώিāϤ āϕ⧰া āĻļāĻ•্āϤিā§° āĻĻā§°ে āĻāĻ•ে? āĻ•িāϝ়?

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5. If the moon attracts the earth, why does the earth not move towards the moon?  

āϝāĻĻি āϚāύ্āĻĻ্ā§°āχ āĻĒৃāĻĨিā§ąীāĻ• āφāϕ⧰্āώিāϤ āϕ⧰ে, āĻĒৃāĻĨিā§ąী āĻ–āύ āϚāύ্āĻĻ্ā§°ā§° āĻĢাāϞে āĻ•িāϝ় āύাāϝাāϝ়?  

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6. What happens to the force between two objects, if (i) the mass of one object is doubled? (ii) the distance between the objects is doubled and tripled? (iii) the masses of both objects are doubled?

āϝāĻĻি (āφāχ) āĻāϟা āĻŦāϏ্āϤুā§° āĻ­ā§° āĻĻুāĻ—ুāĻŖ āĻšāϝ়, āϤেāύ্āϤে āĻĻুāϟা āĻŦāϏ্āϤুā§° āĻŽাāϜ⧰ āĻŦāϞ⧰ āĻ•ি āĻš'āĻŦ? (āφāχāφāχ) āĻŦāϏ্āϤুāĻŦোā§°ā§° āĻŽাāϜ⧰ āĻĻূā§°āϤ্āĻŦ āĻĻুāĻ—ুāĻŖ āφ⧰ু āϤিāύিāĻ—ুāĻŖ āϕ⧰া āĻšāϝ়? (āϤৃāϤীāϝ়) āĻĻুāϝ়োāϟা āĻŦāϏ্āϤুā§° āĻ­ā§° āĻĻুāĻ—ুāĻŖ āϕ⧰া āĻšāϝ়?

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 7. What is the importance of universal law of gravitation?

āĻŽāĻšাāϕ⧰্āώāĻŖā§° āϏাā§°্āĻŦāϜāύীāύ āύিāϝ়āĻŽā§° āĻ—ুā§°ুāϤ্āĻŦ āĻ•ি?

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8. What is the acceleration of free fall? 

āĻŽুāĻ•্āϤ āĻĒāϤāύ⧰ āϤ্āĻŦā§°āĻŖ āĻ•ি? 

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9. What do we call the gravitational force between the earth and an object?

 āφāĻŽি āĻĒৃāĻĨিā§ąী āφ⧰ু āĻŦāϏ্āϤুāĻāϟাā§° āĻŽাāϜ⧰ āĻŽাāϧ্āϝাāϕ⧰্āώāĻŖ āĻļāĻ•্āϤিāĻ• āĻ•ি āĻŦুāϞি āĻ•āĻ“ঁ?

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10. Amit buys few grams of gold at the poles as per the instruction of one of his friends. He hands over the same when he meets him at the equator. Will the friend agree with the weight of gold bought? If not, why? [Hint: The value of g is greater at the poles than at the equator.] 11. Why will a sheet of paper fall slower than one that is crumpled into a ball?

āĻ…āĻŽিāϤে āϤেāĻ“ঁā§° āĻāϜāύ āĻŦāύ্āϧুā§° āύিā§°্āĻĻেāĻļāύা āĻ…āύুāϏ⧰ি āĻ–ুāϟাāĻŦোā§°āϤ āĻ•েāχāĻ—্ā§°াāĻŽ āϏোāĻŖ āĻ•্ā§°āϝ় āϕ⧰ে। āϝেāϤিāϝ়া āϤেāĻ“ঁ āĻŦিāώুā§ą ā§°েāĻ–াāϤ āϞāĻ— āĻĒাāϝ় āϤেāϤিāϝ়া āϤেāĻ“ঁ āĻāĻ•েāϟা āĻšāϏ্āϤাāύ্āϤ⧰ āϕ⧰ে। āĻŦāύ্āϧুāϜāύে āĻ•িāύা āϏোāĻŖā§° āĻ“āϜāύ⧰ āϏৈāϤে āϏāύ্āĻŽāϤ āĻš'āĻŦāύে? āϝāĻĻি āύāĻšāϝ়, āĻ•িāϝ়? [āχāĻ™্āĻ—িāϤ: āĻŦিāώুā§ąā§°েāĻ–াāϤāĻ•ৈ āĻŽেā§°ুāϤ āϜি-ā§° āĻŽূāϞ্āϝ āĻ…āϧিāĻ•।]

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12. Gravitational force on the surface of the moon is only as strong as gravitational force on the earth. What is the weight in newtons of a 10 kg object on the moon and on the earth? 

āϚāύ্āĻĻ্ā§°āĻĒৃāώ্āĻ āϤ āĻŽাāϧ্āϝাāϕ⧰্āώāĻŖāĻļāĻ•্āϤি āĻ•েā§ąāϞ āĻĒৃāĻĨিā§ąীā§° āĻŽাāϧ্āϝাāϕ⧰্āώāĻŖāĻļāĻ•্āϤিā§° āĻĻā§°েāĻļāĻ•্āϤিāĻļাāϞী। āϚāύ্āĻĻ্ā§° āφ⧰ু āĻĒৃāĻĨিā§ąীāϤ 10 āĻ•িāϞোāĻ—্ā§°াāĻŽ āĻŦāϏ্āϤুā§° āύিāωāϟāύ⧰ āĻ“āϜāύ āĻ•িāĻŽাāύ? 

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13. A ball is thrown vertically upwards with a velocity of 49 m/s. Calculate (i) the maximum height to which it rises, (ii) the total time it takes to return to the surface of the earth. 

āĻŦāϞ āĻāϟা 49 āĻŽিāϟাā§°/āĻ›ে āĻŦেāĻ—ā§° āϏৈāϤে āωāϞāĻŽ্āĻŦāĻ­াā§ąে āĻ“āĻĒā§°āϞৈ āĻĻāϞিāϝ়াāχ āĻĻিāϝ়া āĻšāϝ়। (āφāχ) āχ āϝি āωāϚ্āϚāϤাāϞৈ āωāĻ িāĻ›ে āĻ—āĻŖāύা āϕ⧰āĻ•, (āφāχāφāχ) āĻĒৃāĻĨিā§ąীā§° āĻĒৃāώ্āĻ āϞৈ āϘূā§°ি āφāĻšিāĻŦāϞৈ āϞāĻ—া āĻŽুāĻ  āϏāĻŽāϝ়।

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14. A stone is released from the top of a tower of height 19.6 m. Calculate its final velocity just before touching the ground.

⧧⧝.ā§Ŧ āĻŽিāϟাā§° āωāϚ্āϚāϤাā§° āĻāϟা āϟাā§ąাā§°ā§° āĻ“āĻĒā§°ā§° āĻĒā§°া āĻāϟা āĻļিāϞ āĻā§°ি āĻĻিāϝ়া āĻšāϝ়। āĻŽাāϟি āϏ্āĻĒā§°্āĻļ āϕ⧰াā§° āĻ িāĻ• āφāĻ—āϤে āχāϝ়াā§° āĻ…āύ্āϤিāĻŽ āĻŦেāĻ— āĻ—āĻŖāύা āϕ⧰āĻ•।

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15. A stone is thrown vertically upward with an initial velocity of 40 m/s. Taking g= 10 m/s², find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone?

40 āĻŽিāϟাā§°/āĻ›েāĻ•েāĻŖ্āĻĄā§° āĻĒ্ā§°াā§°āĻŽ্āĻ­িāĻ• āĻŦেāĻ—ā§° āϏৈāϤে āĻāϟা āĻļিāϞ āωāϞāĻŽ্āĻŦāĻ­াā§ąে āĻ“āĻĒā§°āϞৈ āĻĻāϞিāϝ়াāχ āĻĻিāϝ়া āĻšāϝ়। āĻ—্ā§°াāĻŽ= 10 āĻŽিāϟাā§°/āĻ›ে² āĻ—্ā§°āĻšāĻŖ āϕ⧰ি, āĻļিāϞāϟোā§° āĻĻ্āĻŦাā§°া āϏ⧰্āĻŦাāϧিāĻ• āωāϚ্āϚāϤা āĻĒ্ā§°াāĻĒ্āϤ āϕ⧰āĻ•। āĻļিāϞে ā§°ে āĻ–াāĻĒ āĻ–াāϝ় āύেāϟ āϏ্āĻĨাāύাāύ্āϤ⧰ āφ⧰ু āĻŽুāĻ  āĻĻূā§°āϤ্āĻŦ āĻ•িāĻŽাāύ?

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16. Calculate the force of gravitation between the earth and the Sun, given that the mass of the earth = 6 x 1024 kg and of the Sun = 2 x 1030 kg. The average distance between the two is 1.5 x 10¹¹ m.

āĻĒৃāĻĨিā§ąী āφ⧰ু āϏূā§°্āϝ⧰ āĻŽাāϜ⧰ āĻŽāĻšাāϕ⧰্āώāĻŖāĻļāĻ•্āϤি āĻ—āĻŖāύা āϕ⧰āĻ•, āϝিāĻšেāϤু āĻĒৃāĻĨিā§ąীā§° āĻ­ā§° = 6 āĻĻāĻļāĻ• 1024 āĻ•িāĻ—্ā§°া āφ⧰ু āϏূā§°্āϝ⧰ = 2 āĻĻāĻļāĻ• 1030 āĻ•িāĻ—্ā§°া। āĻĻুāϝ়োāϟাā§° āĻŽাāϜ⧰ āĻ—āĻĄ় āĻĻূā§°āϤ্āĻŦ āĻšৈāĻ›ে 1.5 āĻāĻ•্āϏ 10¹¹ āĻŽিāϟাā§°।



17. A stone is allowed to fall from the top of a tower 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m/s. Calculate when and where the two stones will meet.

āĻāϟা āĻļিāϞ 100 āĻŽিāϟাā§° āĻ“āĻ– āϟাā§ąাā§°ā§° āĻ“āĻĒā§°ā§° āĻĒā§°া āĻĒā§°িāĻŦāϞৈ āĻĻিāϝ়া āĻšāϝ় āφ⧰ু āĻāĻ•ে āϏāĻŽāϝ়āϤে āφāύ āĻāϟা āĻļিāϞ 25 āĻŽিāϟাā§°/āĻ›ে āĻŦেāĻ—ā§° āϏৈāϤে āĻŽাāϟিā§° āĻĒā§°া āωāϞāĻŽ্āĻŦāĻ­াā§ąে āĻ“āĻĒā§°āϞৈ āĻĒ্ā§°āĻ•্āώেāĻĒ āϕ⧰া āĻšāϝ়। āĻļিāϞ āĻĻুāϟা āĻ•েāϤিāϝ়া āφ⧰ু āĻ•'āϤ āϞāĻ— āĻš'āĻŦ āĻ—āĻŖāύা āϕ⧰āĻ•।

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18. A ball thrown up vertically returns to the thrower after 6 s. Find

(a) the velocity with which it was thrown up,

(b) the maximum height it reaches, and

(c) its position after 4 s.

āωāϞāĻŽ্āĻŦāĻ­াā§ąে āĻĻāϞিāϝ়াāχ āĻĻিāϝ়া āĻāϟা āĻŦāϞ ā§Ŧ āĻ›েāĻ•েāĻŖ্āĻĄā§° āĻĒিāĻ›āϤ āĻĨ্ā§°'āϝ়াā§°āϞৈ āϘূā§°ি āφāĻšে। āĻŦিāϚাā§°

(āĻ•) āχāϝ়াāĻ• āϝি āĻŦেāĻ—েā§°ে āĻĒেāϞাāχ āĻĻিāϝ়া āĻšৈāĻ›িāϞ,

(āĻ–) āχ āϏ⧰্āĻŦাāϧিāĻ• āωāϚ্āϚāϤাāϤ āωāĻĒāύীāϤ āĻšāϝ়, āφ⧰ু

(āĻ—) 4 āĻ›ে.-ā§° āĻĒিāĻ›āϤ āχāϝ়াā§° āϏ্āĻĨিāϤি।

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19. In what direction does the buoyant force on an object immersed in a liquid act?

āϤ⧰āϞ āĻĒāĻĻাā§°্āĻĨāϤ āύিāĻŽāϜ্āϜিāϤ āĻŦāϏ্āϤু āĻāϟাā§° āĻ“āĻĒā§°āϤ āωāϚ্āĻ›āϞ āĻļāĻ•্āϤিāϝ়ে āĻ•ি āĻĻিāĻļāϤ āĻ•াāĻŽ āϕ⧰ে?

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20. Why does a block of plastic released under water come up to the surface of water?

āĻĒাāύীā§° āϤāϞāϤ āĻā§°ি āĻĻিāϝ়া āĻĒ্āϞাāώ্āϟিāϕ⧰ āĻāϟা āĻ–āĻŖ্āĻĄ āĻĒাāύীā§° āĻĒৃāώ্āĻ āϞৈ āĻ•িāϝ় āφāĻšে?

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21. The volume of 50 g of a substance is 20 cm³. If the density of water is 1 g cm³, will the substance float or sink?

āĻĒāĻĻাā§°্āĻĨ āĻāϟাā§° 50 āĻ—্ā§°াāĻŽā§° āĻĒā§°িāĻŽাāĻŖ āĻšৈāĻ›ে 20 āϚেāĻŽি³। āϝāĻĻি āĻĒাāύীā§° āϘāύāϤ্āĻŦ 1 āĻ—্ā§°াāĻŽ āĻ›েāĻŽি³ āĻšāϝ়, āĻĒāĻĻাā§°্āĻĨāϟো āĻ­াঁāĻšি āĻĨাāĻ•িāĻŦ āύে āĻĄুāĻŦ āϝাāĻŦ?

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22. The volume of a 500 g sealed packet is 350 cm³. Will the packet float or sink in water if the density of water is 1 g cm 3? What will be the mass of the water displaced by this packet?,  

500 āĻ—্ā§°াāĻŽ āϚীāϞ āϕ⧰া āĻĒেāĻ•েāϟāĻāϟাā§° āφāϝ়āϤāύ āĻšৈāĻ›ে 350 āϚেāĻŽি³। āϝāĻĻি āĻĒাāύীā§° āϘāύāϤ্āĻŦ 1 āĻ—্ā§°াāĻŽ āϚেāĻŽি 3 āĻšāϝ় āϤেāύ্āϤে āĻĒেāĻ•েāϟāϟো āĻ­াঁāĻšি āĻĨাāĻ•িāĻŦ āύে āĻĒাāύীāϤ āĻĄুāĻŦ āϝাāĻŦ? āĻāχ āĻĒেāĻ•েāϟāϟোā§° āĻĻ্āĻŦাā§°া āϏ্āĻĨাāύāϚ্āϝুāϤ āĻšোā§ąা āĻĒাāύীā§° āĻ­ā§° āĻ•িāĻŽাāύ āĻš'āĻŦ?,     

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Question Type By- Parina Hazarika                     


Post Id: DABP002935