Physics XI Karachi Board True and False - Chapter 6

Chapter 6 - Gravitation
1. Newton made the hypothesis that every body in the universe exerts a gravitation force of attraction on every other body.

2. The moon’s orbit is about circular.

3. The moon is freely falling to earth.

4. The time taken by the moon to complete one revolution around the earth is 2.36 x 106 seconds.

5. The acceleration of the moon is about 2.72 x 10-3 m/s2.

6. The value of orbits radius of the moon is about 3.84 x 106m.

7. The centripetal acceleration of the moon is given by 4p2R/T.

8. According to the law of gravitation the force of attraction between the two bodies is directly proportional to the sum of their masses.

9. According to the law of gravitation the force of attraction between two bodies is inversely proportional to the square of the distance between their centres.

10. The force with which the earth attracts any body towards its centre is called its weight.

11. The value of g increases with the increase of the distance from the centre of the earth.

12. The value of gravitational constant is 6.673 x 1011 N-m2 /kg2.

13. If the cable carrying the elevator breaks, the elevator descends with acceleration equal to ‘g’.

14. The force of gravity on a body varies slightly from place to place on earth for two reasons, first the shape of the earth and secondly its rotation.

15. Acceleration due to gravity decreases at a faster rate for a point above the surface of earth than for the same point below the surface of earth.

16. Weight of body is a vector quantity.

17. The magnitude of the weight is expressed in the units of force such as Newton.

18. The gravitational force is responsible for the motion of the planets around the sun.

19. An Astronaut in a satellite orbitting the earth experiences a state of weightlessness because the satellite orbitting with a centripetal acceleration equal to ‘g’.

20. Artificial gravity is produced in satellite by spinning it abut its own axis.


21. If the mass of the earth becomes four times then the value of g will be doubled.

22. The acceleration due to gravity varies with latitude on the Earth.

23. Planets revolve round the sun due to gravitational attraction between sun and the planets.

24. Spring balance is used to measure the apparent weight of the body.

25. The value of ‘g’ is directly proportional to the square of the radius of earth.

26. The acceleration due to gravity on moon is about one-fourth the acceleration due to gravity on the surface of the earth.

27. Acceleration due to gravity at the centre of the earth is zero.

28. On the surface of the moon the weight of a body increases as compare to its weight on earth.

29. The value of gravitational acceleration at a distance equal to earth, radius above the earth’s surface is one fourth that of on the surface of the earth.

30. The weight of a body at the pole is greater than at equator.

31. The gravitational pull at equator is more than at poles.

32. The gravitational force of attraction between the two bodies does not depend upon their shape.

33. Weightlessness in artificial satellite is due to out of reach of gravity.

34. The force required to prevent a body from falling or accelerating in a frame of reference is called the apparent weight of the body.

35. When a frame of reference is ascending with a constant acceleration then the apparent weight of the body increases.