Physics-DPP-2-Gravitation

PHYSICS Topic: GRAVITATION Date: 1. A body which is initially at rest at a height R above the surface of the earth of radius R, falls freely towards the earth, then its velocity on reaching the surface of the earth is : 2. What additional velocity must be given to a satellite orbiting around earth with radius R to become free from earth’s gravitational field. Mass of earth is M. (a) GM 2 - 1 R (b) GM 2R 2 - 1) (c) GM 3 - 1 R (d) GM 2 + 1 R 3. What impulse need to be given to a body of mass m, released from the surface of earth along a straight tunnel passing through centre of earth, at the centre of the earth, to bring it to rest. (Mass of earth M, radius of earth R) (a) m (b) (c) m (d) zero 4. A point P(R 3, 0, 0) lies on the axis of a ring of mass M and radius R. The ring is located in y-z plane with its centre at origin O. A small particle of mass m starts from P and reaches O under gravitational attraction only. Its speed at O will be : (a) (b) (c) (d) 5. A solid sphere of uniform density and radius R applies a gravitational force of attraction equal to F1 on a particle placed at a distance R 2 R from the centre of the sphere. A spherical cavity of radius 2 is now made in the sphere as shown in the figure. The sphere with F2 cavity now applies a gravitational force F2 on the same particle. The ratio is : 1 (a) 5 9 (b) 7 8 (c) 3 7 4 (d) 9 6. When a satellite going round the earth in a circular orbit of radius r and speed v loses some of its energy, then r and v change as : (a) r and v both will increase (b) r and v both will decrease (c) r will decrease and v will increase (d) r will increase and v will decrease 7. A particle hanging from a massless spring stretches it by 2 cm at earth’s surface. How much will the same particle stretch the spring at height 2624 km from the surface of earth ? (Radius of earth = 6400 km) (a) 1 cm (b) 2 cm (c) 3 cm (d) 4 cm PHYSICS Topic: GRAVITATION Date: 8. A satellite is revolving in a circular orbit whose radius is R work done by gravitatioanl force in the revolution is (a) zero (b) 2 mGR2 (c) mg R2 (d) mg R 9. Three solid spheres each of mass m and radius R are released from the position shown in figure. The speed of any one sphere at the time of collision would be : - 10. A satellite of mass ms revolving in a circular orbit of radius rs around the earth of mass M has a total energy E. Then its angular momentum will be : E (a) (b) 2m r 2 (c) (d) PHYSICS Topic: GRAVITATION Date: 1. (b) 2. (a) Answer Key 3. (a) 4. (a) 5. (d) 6. (c) 7. (a) 8. (a) 9. (d) 10. (c)

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