Ncert – class 9- science – Chapter 9 – Gravitation 1 Welcome to your Ncert - class 9- science - Chapter 9 – Gravitation 1 1. Which of the following statements should be correct for a rocket fired from the earth towards the moon ? The value of g keeps decreasing as the rocket goes to the Moon The value of g first decreases and as the rocket approaches the Moon the value of g increases but now the direction is towards the Moon. The value of g keeps increasing as the rocket goes to the Moon The value of g remains constant throughout the path of the rocket None 2. If the force of gravity suddenly disappears:- The mass of all bodies will become zero The weight of all bodies will become zero Both mass and weight of all bodies will become zero Neither mass nor weight of all bodies will become zero None 3. Who among the following did first give the experimental value of G? None of these Capernicus Cavendish Brook Taylor None 4. Which of the following is an application of Archimedes' principle? Used in Hydrometer All of these Used in Lactometers Used in designing ships and submarines None 5. A person weighs 110.84 N on the moon whose acceleration due to gravity is one-sixth of that earth if the value of g on earth is 9.8 ms −2 calculate, acceleration due to gravity on the earth. 2.89 ms −2 1.63 ms −2 2.63 ms −2 1.89 ms −2 None 6. At the surface of a certain planet acceleration due to gravity is one-quarter of that on the earth. If a brass ball is transported to this planet, then which one of the following statements is not correct? The brass ball has same mass on the other planet as on the earth The mass of the brass ball on this planet is quarter of its mass as measured on the earth None of the above The brass ball has same volume on the other planet as on the earth None 7. A body of mass 10 kg is thrown up with a velocity 98ms −1. Simultaneously another is dropped from a tower. After 2 seconds their momenta are found to be same in magnitude. Then the mass of the freely falling body is 30 kg 4 kg 20 kg 40 kg None 8. The moon's radius is 1/4 times that of the earth and its mass 1/80 times that of the earth. If g represents the acceleration due to gravity on the surface of the earth, then on the surface of the moon its value is : g/5 g/8 g/6 g/4 None 9. If water falls from a tap, then the volume rate of flow of water at depth of ℎ, \((A_{0})\)is the area of cross-section of the mouth and \(A_{0}/2\) is the corresponding area at depth ℎ) $$2A_{0}\sqrt{gh}$$ $$A_{0}\sqrt{3gh}$$ $$A_{0}\sqrt{\frac{2}{3}gh}$$ $$A_{0}\sqrt{2gh}$$ None 10. Why do hot air ballons rise and float mid-air? None of these The buoyant force of the hot-air balloon is less than the surrounding air The buoyant force of the hot-air balloon is equal to the surrounding air The buoyant force of the hot-air balloon is more than the surrounding air None 11. Four marbles are dropped from the top of a tower one after the other with an interval of one second. The first one reaches the ground after 4 seconds. When the first one reaches the ground the distances between the first and second, the second and third and the third and fourth will be respectively 40, 30 and 20 m 30, 20 and 10 m 20, 10 and 5 m 35, 25 and 15 m None 12. Two point masses A and B have masses in the ratio of 1 : 4 .The point masses are at distance 1 m apart. At what distance from point mass B. a point mass m is placed so that at that point the resultant force on it zero ? 2/5 m 1/5 m 1/3 m 2/3 m None 13. Which of the following can be used for measuring the weight of an object? Thermometer Spring Balance Odometer Speedometer None 14. The weight of a person reduces to one-sixth on the Moon than on the Earth What changes will you notice in the mass of a person on the Moon in comparison to the Earth? The mass of the person remains unchanged on the moon The mass of the person reduces to one sixth on the moon like weight The mass of the person reduces to one fourth on the moon The mass of the person reduces to half on the moon None 15. Which of the following statements about the gravitational constant is true It has same value in all systems of units It does not depend on the nature of the medium in which the bodies are kept. It is a force It has no unit None 16. A body falls from height h=200 m. The ratio of distance travelled in each 2 s, during t=0 to t=6 s of the journey is (g=10m/s 2 ): 1:3:5 1:2:4 1:4:9 1:2:3 None 17. A body of mass m is taken to the bottom of a deep mine. Then Its weight decreases Its weight increases Its mass increases Its mass decreases None 18. A small spherical ball of radius r falls freely under gravity through a distance of ℎ before entering a tank of water. If, after entering the water, the velocity of the ball does not change, then ℎ is proportional \(r^{3}\) \(r^{2}\) \(r^{5}\) \(r^{4}\) None 19. A ball is dropped from the top of building. The ball takes 0.5s to fall post the 3m length of window some distance from the top of the building. If the velocity of the ball at the top and at the bottom of the window are \(V _{T} and V_{B}\) respectively, then \(V _{T} + V_{B}=4.9ms^{-1}\) \(V _{T} × V_{B}=12ms^{-1}\) \(V _{T} × V_{B}=1ms^{-1}\) \(V _{T} + V_{B}=12ms^{-1}\) None 20. The maximum height from which a person can safely jump is 2.45 m. What is the maximum allowable landing speed for a parachutist? 4.93 m/s 69.3 m/s 5.93 m/s 6.93m/s None Time's up Please Share This Share this content Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Leave a Reply Cancel replyCommentEnter your name or username to commentEnter your email address to commentEnter your website URL (optional) Save my name, email, and website in this browser for the next time I comment.
