Ncert – class 9- science – Chapter 9 – Gravitation 2 Welcome to your Ncert – class 9- science – Chapter 9 – Gravitation 2 1. Suppose universal gravitational constant of starts decrease, then: All of the above Earth will follow a spiral path of decreasing radius Length of the year will increase Kinetic energy of earth will decrease None 2. 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 3. Newton's law of gravitation is called the universal law of gravitation because: it is applicable to all particles and members of the solar family it is applicable for all masses at all distances, independent of the medium None of these it is always valid for forces of attraction None 4. 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. $$\frac{6g}{4G\pi R}$$ $$\frac{2g}{4G\pi R}$$ $$\frac{3g}{4G\pi R}$$ $$\frac{3g}{8G\pi R}$$ None 5. 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: 200N 80N 150N 100N None 6. The mass of an object ................ is in the direction of gravitational force. varies at different locations can be measured using a spring balance remains constant None 7. Construction of submarines is based on Archimedes principle Pascals law Newtons laws Bernoullis theorem None 8. If a rock is brought from the surface of the moon. its mass and weight both will remain same both mass and weight will change its mass will change its weight will change but not mass None 9. 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 5000 N 4000 N 1000 N None 10. 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? 1 16 18 2 None 11. 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? 0N 20 N 60 N 10N None 12. 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 maximum Mass does not change, weight is maximum Mass does not change, weight is minimum Both mass and weight are minimum None 13. Relative density of a substance is expressed by comparing the density of that substance with the density of: Iron Water Mercury Air None 14. 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: $$\frac{m}{M}$$ 1:1 $$\frac{mr}{M}$$ $$\frac{M}{m}$$ None 15. 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 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.
