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IIT JEE Gravitation part 2

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1. Two satellite move in circular orbits around the Earth at distance 9000 km and from the centre of Earth. If the nearer satellite has a period of revolution of 90 minutes around the Earth then the difference in the period of revolution around the Earth is




2. What is the weight of a body at a distance 2r from the centre of the Earth if the gravitational potential energy of the body at a distance r from the centre of the Earth is U ?




3. The diameters of two planets are in the ratio of 4 : 1. Their mean densities are in the ratio 1 : 2. The ratio of accelerations due to gravity on the planets is




4. If the Earth suddenly shrinks to half of its present radius then the acceleration due to gravity will be




5. The increase in gravitational potential energy of an object of mass m raised from the surface of Earth to a height equal to the radius R of Earth is




6. A man weighs W on the surface of Earth. What is his weight at a height equal to R ?




7. The accentricity of Earth s orbit is 0.017. The ratio of the maximum speed in its orbit to its minimum speed is




8. The ratio of the kinetic energy required to be given to a satellite so that it escapes the gravitational field of Earth to the kinetic energy required to put the satellite in a circular orbit just above the free surface of Earth is




9. A satellite is revolving in an orbit close to the surface of Earth with kinetic energy K. When the kinetic energy is increased to nK the satellite escapes. What is the minimum value of n ?




10. A satellite in a circular orbit of radius R has period 4 hours. A satellite of orbit radius 4R around the same planet will have period




11. Masses of 1 kg each are placed 1 m 2m 4 m 8 m??from a point P. The gravitational field intensity at P due to these masses is




12. An object weighs 98 N at the north pole of Earth. What is its true weight in a geostationary satellite whose distance from the centre of Earth is 7R where R is the radius of the Earth ?




13. If Earth describes an orbit round the Sun of double its present radius the year on Earth will be of




14. A satellite is launched in a circular orbit of radius R and another satellite is launched in circular orbit of radius 1.01 R. The time period of second satellite is different from that of the first satellite by




15. A body is orbiting around the Earth at a mean radius 16 times as great as the parking orbit of a satellite. The period of the body is




16. In order to shift a body of mass m from a circular orbit of radius 3R to a orbit of radius 5R around the Earth the work done is




17. The K.E. of a satellite is 2 MJ. What is the total energy of the satellite ?




18. Suppose Earth s orbit motion around the Sun is suddenly stopped. What time the Earth shall take to fall into the Sun ?




19. Radius of the Earth is 6000 km. Weight of a body on the surface of Earth is 120 kg wt. If it is taken to a height of 2000 km above the surface of Earth its weight is




20. The ratio of the radius of the Earth to that of moon is 10. The ratio of acceleration due to gravity on Earth and on Moon is 6. The ratio of the escape velocity from the surface of Earth to that from the Moon is




21. The gravitational potential energy of a body of mass m at a distance r from the centre of the Earth is U. What is the weight of the body at this distance ?




22. The radius of the Earth shrinks by 1% its mass remaining the same. The percentage change in the value of g is




23. Suppose Moon s orbital motion around the earth is suddenly stopped. What time the Moon shall take to fall on to the Earth ?




24. The value of g at a certain height h above the free surface of Earth is x / 4 where x is the value of g at the surface of Earth. The height h is




25. A satellite is circling around the Earth at a distance x from the centre of Earth. If the radius of the circular orbit is reduced by 1% then the speed will increase by




26. Two satellite A and B go around a planet P in circular orbits having radii 4R and R respectively. If the speed of the satellite A is 3v the speed of satellite B would be




27. A satellite of mass m is revolving round the Earth at a height R above the surface of the Earth. If g is the gravitational intensity at the earth surface and R is the radius of the Earth then the kinetic energy of the satellite will be




28. Explorer 38 a radio-astronomy satellite of mass 200 kg circles the Earth in an orbit of average radius 3R / 2 where R is the radius of the Earth. Assuming the gravitational pull on a mass of 1 kg at the earths surface to be 10 N calculate the pull on the satellite




29. A communication satellite is put in an orbit around the Earth. What is the approximate time taken by a radiowave to go to the satellite and come back to the Earth ?




30. The gravitational potential difference between the surface of a planet and a point 20 m above the surface is 2 joule/kg. If the gravitational field is uniform then the work done in carrying a 5 kg body to a height of 4 m above the surface is




31. A missile which missed its target went into orbit around the Earth at a mean radius 4 times as great as the parking orbit of a satellite. The period of the missile is




32. An artificial satellite is moving in a circular orbit around the Earth with a speed equal to half the magnitude of escape velocity from the Earth. The height of satellite above the surface of Earth is (where R = radius of Earth.)




33. The force of gravitational attraction between the Earth and a geostationary satellite of mass 1 quintal is nearly




34. The period of revolution of planet A around the Sun is 8 times that of B. The distance of A from the Sun is n times greater than the distance of B from the Sun. The value of n is




35. What is the percentage change in the value of g as we shift from equator to pole on the surface of Earth ? (Given : Equatorial radius of Earth is greater than polar radius by 21 km and mean radius of Earth = 6300 km)




36. A body is raised to a height h so that the force of gravity on body is 1% of the value on the surface of Earth. If the radius of the Earth is 6400 km then the value of h is




37. research satellite of mass 200 kg circles the Earth in an orbit of average radius 3R/2 where R is the radius of the Earth. Assuming the gravitational pull on a mass 1 kg on Earth s surface to be 10 N the pull on the satellite will be




38. A mass m is raised from the surface of Earth to a point which is at a height nR from the surface of Earth. Change in potential energy is




39. A body weighs 63 N on the surface of the Earth. At a height h above the surface of Earth its weight is 28 N while at a depth h below the surface of Earth the weight is 31.5 N. The value of h is