Gravitation Mock Test – Class 11 Physics

1. The following choices compare gravity and apparent weight in a satellite.

The table is

2. A body weighs on Earth’s surface. It is taken to a planet with twice Earth’s density and half Earth’s radius. Its weight there is

3. A mass is moved slowly from distance to distance from a fixed mass . The work done by gravitational force is

4. A satellite is in a circular orbit of radius around a planet. Its speed is suddenly reduced to of the circular speed at the same point. The new total mechanical energy immediately after reduction is

5. The relation between escape speed and circular orbital speed at the same radius around the same planet is

6. A planet has uniform density and radius . Its surface gravity is

7. A graph is drawn with on the horizontal axis and surface gravity on the vertical axis for planets having the same radius . The expected graph is

8. Consider these statements about applying superposition to gravitational forces.
I. Each source mass exerts its force on the test mass independently.
II. The net force is obtained by scalar addition only.
III. Symmetric arrangements can give zero net force even though individual forces are nonzero.
The suitable option is

9. A satellite is in a circular orbit of radius . It is then made to escape from the same radius. The added energy is smaller than the energy needed to escape from rest at the same radius because the satellite already has

10. The binding energy of a satellite in a circular orbit of radius is

11. A satellite of mass moves in a circular orbit where and . Its binding energy is

12. A satellite orbits a planet of mean density just above its surface. Its time period depends on density as

13. If the separation between two masses changes from to , the gravitational potential energy changes from to

14. Assertion: A planet in an elliptical orbit moves faster when it is nearer the Sun. Reason: The line joining the planet and the Sun sweeps equal areas in equal time intervals.

15. Two satellites of equal mass orbit the same planet in circular orbits of radii and . The ratio of their angular momenta is

16. A planet has mass and radius . A body is projected vertically upward from the surface with speed . Its maximum height above the surface is

17. An object is moved from the equator to the pole. Ignoring local geological variations, its mass and weight change as

18. The direction of at a point close to Earth’s surface is best described as

19. A spring balance carrying a small block is kept inside a freely orbiting satellite. The balance reading is nearly zero because

20. A satellite orbits Earth in a circle at radius . If a near-surface circular orbital speed is , the satellite’s orbital speed is

21. A satellite is in a circular orbit of radius . Its kinetic energy is . If the satellite is shifted to a circular orbit of radius , its new kinetic energy is

22. For a body projected from distance from the centre of a planet of mass , the escape speed is

23. A planet has density and radius . Planet has density and radius . The ratio of their escape speeds is

24. Kepler’s second law states that the line joining a planet and the Sun sweeps out

25. A set of graph observations says: falls by a factor of when triples, becomes one-third when triples, and becomes times when triples for circular orbits around the same mass. The record is

26. A low-orbit satellite has local gravitational acceleration , yet a loose object inside it appears weightless. The best explanation is that

27. A body has gravitational mass and inertial mass . Near Earth, the gravitational force is . Its acceleration would be

28. A passage says: “A spacecraft at radius has . Therefore it can escape because gravity exactly provides centripetal force.” The missing condition is that escape from the same radius requires

29. A body is taken from the surface of a planet to a point where the escape speed is half the surface escape speed. The height above the surface is

30. In a circular satellite orbit, the acceleration is toward Earth’s centre while the velocity is tangential. The angle between acceleration and velocity is

31. A student adds two gravitational pulls of and as without checking directions. If the two pulls are perpendicular, the actual resultant is

32. The table gives four arrangements of source masses around a test mass . Each source mass is at the same distance from .

The cases with zero net gravitational force on are

33. A spacecraft in a circular orbit fires its engine briefly so that its speed becomes the local escape speed at the same radius. If the original orbital speed is , the required new speed is

34. If only Earth’s shape is considered, is smaller at the equator than at the poles because

35. A student’s error list says:
I. for two attracting masses.
II. with zero at infinity.
III. for gravitational force.
The entries needing correction are

36. Taking and , the time period of a satellite just above Earth’s surface is closest to

37. A satellite’s orbital radius is doubled. The ratio of its new orbital speed, escape speed from that radius, and period to their original values is

38. Use the arrangement described below: mass is placed at the left end of a horizontal line and mass is placed at the right end. The force on due to is directed

39. A planet has mass and radius . If Earth’s surface gravity is , the planet’s surface gravity is

40. A body starts from rest at a distance from the centre of a planet of mass and falls radially inward to a distance . Its speed at is

41. A uniform spherical planet has mass , radius , and surface gravity . At an interior point whose distance from the centre is , the potential difference between that point and the surface is

42. Two fixed masses and are separated by distance . At the point between them where the net gravitational field is zero, the gravitational potential is

43. A body has mass on Earth. If it is taken to a planet where is one-third of Earth’s value, its mass and weight become

44. A satellite moves in a circular orbit of radius . Its angular momentum about the planet’s centre is . In a new circular orbit of radius , its angular momentum becomes

45. Assertion: The period of a circular satellite at a fixed orbital radius is smaller around a more massive planet. Reason: .

46. The Moon does not fall straight down to Earth mainly because it has

47. For a uniform solid sphere of radius , the gravitational field magnitude inside the sphere varies with distance from the centre as

48. The statement that best contrasts altitude and depth variation of is

49. The potential inside a uniform solid sphere of mass and radius may be written as . At the centre, the potential is

50. A point has two gravitational field contributions, east and north. The resultant field magnitude is