Ncert – class 9- science – Chapter 9 – Gravitation 2 Welcome to your Ncert – class 9- science – Chapter 9 – Gravitation 2 1. When an object is thrown up, the force of gravity. Remains constant as the body moves up Acts in the opposite direction ofthe motion Acts in the direction of the motion Increases as the body moves up None 2. Newton's law of gravitation is called the universal law of gravitation because: None of these it is applicable to all particles and members of the solar family it is always valid for forces of attraction it is applicable for all masses at all distances, independent of the medium None 3. If R is the radius of a planet, g is the acceleration due to gravity and G is the gravitational constant then find the density of the planet. $$\frac{3g}{4G\pi R}$$ $$\frac{2g}{4G\pi R}$$ $$\frac{3g}{8G\pi R}$$ $$\frac{6g}{4G\pi R}$$ None 4. The radius of the Earth is about 6400��6400km and that of Mars is about 3200km. The mass of the Earth is about 20 times the mass of Mars. An object weighs 500N on the surface of Earth. Its weight on the surface of Mars would be: 80N 150N 100N 200N None 5. The mass of an object ................ is in the direction of gravitational force. varies at different locations remains constant can be measured using a spring balance None 6. Suppose universal gravitational constant of starts decrease, then: Earth will follow a spiral path of decreasing radius Kinetic energy of earth will decrease All of the above Length of the year will increase None 7. If the masses of two bodies are doubled and the distance between them is halved, then the new gravitational force between them is how many times the original? 16 1 2 18 None 8. A body, the mass and the weight of which were already determined at the Equator, is now placed at the Pole. In this context, choose the correct statement from the following: Both mass and weight are minimum Mass does not change, weight is minimum Mass does not change, weight is maximum Both mass and weight are maximum None 9. Universal gravitational constant, G depends: on the medium present between the particles on time on the nature of the particle does not depend on any of these factors. None 10. If a rock is brought from the surface of the moon. its mass will change its weight will change but not mass its mass and weight both will remain same both mass and weight will change None 11. Construction of submarines is based on Bernoullis theorem Newtons laws Pascals law Archimedes principle None 12. Astronomers have discovered a planet orbiting a nearby star. It is estimated that the mass of this planet is 16 times that of our earth and its density is one-fourth of the earth's density. Assume that planets are spheres of uniform density. If your weight on the earth is 1000 N, then your weight on this planet would be 2000 N 4000 N 5000 N 1000 N None 13. If the weight of a man on earth’s surface is 60 N, then what will be the weight on the surface of the moon? 20 N 0N 60 N 10N None 14. Relative density of a substance is expressed by comparing the density of that substance with the density of: Air Mercury Iron Water None 15. Two masses m and M are kept at a distance r from each other. The ratio of the force exerted on m due to M and that of M due to m is equal to: $$\frac{m}{M}$$ $$\frac{M}{m}$$ 1:1 $$\frac{mr}{M}$$ 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.
