Title Class 09 Science Chapter 10 Gravitation.pdf ✅

Gravitation DPP-01 [Topic: Gravitation, Law of Gravitation, Motion of Objects under Gravitational Force of Earth] Very Short Answer Type Questions 1. Write the formula to find the magnitude of the gravitational force between the earth and an object on the surface of earth. 2. What do you mean by free fall? 3. What do you mean by acceleration due to gravity? 4. How does the force of gravitation between two objects changes when the distance between them is reduced to half? 5. Is the value of ' GG ' constant at all the places? 6. What is the weight of an object of mass 1kg ? 7. What is the value of gravitational acceleration acting on a free falling object? 8. What is value ' G ' and also write its unit? 9. Mass of an object is 10kg. What is its weight on Earth? 10. Why is the weight of an object on the moon is 1 6 th of its weight on earth? 11. You find your mass to be 42kg on a weighing machine. Is your mass greater or less than 42kg ? 12. What do we call the gravitational force between the earth and an object on its surface? 13. A stone is released from the top of a tower of height 19.6m. Calculate its final velocity. Short Answer Type Questions-I 14. The mass of the earth is 6 × 1024kg and that of the moon is 7.4 × 1022kg. If the distance between the earth and the moon is 3.84 × 105km, calculate the force exerted by the earth on the moon. (G = 6.7 × 10−11Nm2kg−2). 15. An object is thrown vertically upwards and rises to a height of 10m. Calculate (ii) the velocity with which the object was thrown upwards and (ii) the time taken by the object to reach the highest point. 16. What is the magnitude of the gravitational force between the earth and a 1kg object on its surface? (Mass of the earth is 6 × 1024kg and radius of the earth is 6.4 × 106m ). 17. The weight of a body on the surface of earth is 10kg. What will be its weight when it is taken at the centre of earth? 18. A ball is thrown up with a speed of 5ms−1. How high will it go before it begins to fall? (gg = 9.8ms−2)
19. What is height of a building if the stone dropped from the roof take 10 seconds to reach the ground? (gg = 9.8ms−2) 20. Explain how weight of an object on the moon will be 1 6 th to that on the earth. 21. An object weighs 10N when measured on the surface of the earth. What will be its weight when measured on surface of moon? 22. Gravitational force acts on all the objects in proportion to their masses. Why then, a heavy object does not fall faster than a lighter object? 23. 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? 24. If the moon attracts the earth, why does the earth not move towards the moon? 25. What is the importance of universal law of gravitation? 26. Amit buys few grams of gold at the pole as per the instruction by 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 he bought? If not, why? [Hint: The value of g is greater at the poles than at the equator.] 27. A ball is thrown vertically upwards with a velocity of 49m/s. Calculate (i) the maximum height to which it rises. (ii) the total time it take to return to the surface of the earth. 28. Calculate the force of gravitation between the earth and the sun, given that the mass of the earth = 6 × 1024kg and of the sun = 2 × 1030kg. The average distance between the two is 1.5 × 1011m. 29. A force of 20N acts upon a body whose weight is 9.8N. What is the mass of a body and how much is its acceleration? 30. A man weighs 1200N on earth. What is his mass? (g = 10ms−2). If he was taken to the moon, his weight will be 200N. What is his mass on the moon? What is the acceleration due to gravity on moon? (Take gg = 10ms−2 ) 31. An object was thrown vertically upwards and reaches a height of 78.4m. Calculate the velocity at which the object was thrown? (g = 9.8m/s2) 32. A ball is released from a height of 1 metre. What time will it take to reach the surface of the earth? 33. Mona weighs 750N on earth: (i) On planet Mars, the force of gravity is 38% of that on Earth. How much will Mona weigh on Mars? (ii) What will be Mona's mass on Earth? (g = 10ms−2) 34. Consider two bodies A and B. The body ' B ' is heavier than body ' A '. Which of the bodies is attracted with a greater force by earth? Which of the two will fall with greater acceleration? Explain.
Short Answer Type Questions-II 35. A car falls off a ledge and drops to the ground in 0.5s. Let g = 10ms−2 (for simplifying the calculations). (i) What is its speed on striking the ground? (ii) What is its average speed during: its fall, i.e., during 0.5s ? (iii) How high is the ledge from the ground? 36. Give six differences between mass and weight. 37. What happens to the force between the two objects, if (i) the mass of one of the objects is doubled. (ii) the distance between the objects is doubled and tripled respectively. (iii) the masses of both the objects are doubled. 38. A stone is thrown vertically upwards with an initial velocity of 40m/s. Taking gg = 10m/s2, find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone? 39. A stone is allowed to fall from the top of a tower 100m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25m/s. Calculate when and where the two stones will meet. 40. A person throws a ball vertically up returns to him after 6 seconds. Find. (a) the velocity with which it was thrown up. (b) the maximum height it reaches. (c) its position after 4s.