Ncert – class 9- science – Chapter 9 – Gravitation 2 Welcome to your Ncert – class 9- science – Chapter 9 – Gravitation 2 1. 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 4000 N 5000 N 1000 N 2000 N None 2. The mass of an object ................ is in the direction of gravitational force. remains constant varies at different locations can be measured using a spring balance None 3. If a rock is brought from the surface of the moon. its mass will change both mass and weight will change its weight will change but not mass its mass and weight both will remain same None 4. 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: Mass does not change, weight is maximum Both mass and weight are maximum Mass does not change, weight is minimum Both mass and weight are minimum None 5. 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. $$\frac{2g}{4G\pi R}$$ $$\frac{3g}{8G\pi R}$$ $$\frac{3g}{4G\pi R}$$ $$\frac{6g}{4G\pi R}$$ None 6. When an object is thrown up, the force of gravity. Acts in the direction of the motion Increases as the body moves up Remains constant as the body moves up Acts in the opposite direction ofthe motion None 7. Relative density of a substance is expressed by comparing the density of that substance with the density of: Air Water Mercury Iron None 8. 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: 150N 200N 100N 80N 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. 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: 1:1 $$\frac{M}{m}$$ $$\frac{m}{M}$$ $$\frac{mr}{M}$$ None 11. Construction of submarines is based on Archimedes principle Newtons laws Bernoullis theorem Pascals law None 12. 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? 10N 60 N 0N 20 N None 13. Newton's law of gravitation is called the universal law of gravitation because: None of these it is always valid for forces of attraction it is applicable for all masses at all distances, independent of the medium it is applicable to all particles and members of the solar family None 14. 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? 18 16 2 1 None 15. Suppose universal gravitational constant of starts decrease, then: Earth will follow a spiral path of decreasing radius Kinetic energy of earth will decrease Length of the year will increase All of the above 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.
