Ncert – class 9- science – Chapter 9 – Gravitation 1 Welcome to your Ncert - class 9- science - Chapter 9 – Gravitation 1 1. Who among the following did first give the experimental value of G? Cavendish Capernicus None of these Brook Taylor None 2. 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 \(r^{3}\) \(r^{2}\) \(r^{4}\) \(r^{5}\) None 3. Which of the following can be used for measuring the weight of an object? Spring Balance Odometer Speedometer Thermometer None 4. 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 half on the moon The mass of the person reduces to one fourth on the moon None 5. 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/6 g/4 g/8 g/5 None 6. If the force of gravity suddenly disappears:- Both mass and weight of all bodies will become zero Neither mass nor weight of all bodies will become zero The weight of all bodies will become zero The mass of all bodies will become zero None 7. 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 \(V _{T} + V_{B}=12ms^{-1}\) \(V _{T} × V_{B}=12ms^{-1}\) \(V _{T} × V_{B}=1ms^{-1}\) \(V _{T} + V_{B}=4.9ms^{-1}\) None 8. Which of the following is an application of Archimedes' principle? Used in Hydrometer Used in Lactometers All of these Used in designing ships and submarines None 9. 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 35, 25 and 15 m 20, 10 and 5 m 40, 30 and 20 m 30, 20 and 10 m None 10. Why do hot air ballons rise and float mid-air? The buoyant force of the hot-air balloon is less than the surrounding air The buoyant force of the hot-air balloon is more than the surrounding air The buoyant force of the hot-air balloon is equal to the surrounding air None of these None 11. 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 40 kg 20 kg 30 kg 4 kg None 12. 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) $$A_{0}\sqrt{\frac{2}{3}gh}$$ $$A_{0}\sqrt{3gh}$$ $$2A_{0}\sqrt{gh}$$ $$A_{0}\sqrt{2gh}$$ None 13. 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 5.93 m/s 6.93m/s 69.3 m/s None 14. 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 15. Which of the following statements about the gravitational constant is true It is a force It has same value in all systems of units It has no unit It does not depend on the nature of the medium in which the bodies are kept. None 16. 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 17. 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 ): 1:2:3 1:3:5 1:2:4 1:4:9 None 18. Which of the following statements should be correct for a rocket fired from the earth towards the moon ? The value of g remains constant throughout the path of the rocket 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 decreasing as the rocket goes to the Moon The value of g keeps increasing as the rocket goes to the Moon None 19. 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 20. 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 volume on the other planet as on the earth None of the above 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 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.
