Physics XI Karachi Board MCQs Chapter 6

Chapter 6 - Gravitation
1. The acceleration due to gravity __________.

(Has the same value every where in space, has the same value every where on the earth, Varies with latitude on the earth)

2. If a planet existed whose mass and radius were both twice that of the earth, then acceleration due to gravity at its surface would be __________.

(4.9 m/s2, 19.6 m/s2, 2.45 m/s2)

3. When the space ship is at a distance equal to twice of the earth’s radius from its centre then the gravitational acceleration is __________.

(4.9 m/s2, 19.6 m/s2, 2.45 m/s2)

4. A hole is drilled through the earth along the diameter and a stone is dropped into it. When the stone is at the centre of the earth it has __________.

(Mass, Weight, Acceleration)

5. Newton’s law of universal gravitation __________.

(Can only be indirectly inferred from the behaviour of the planent, Can be directly verified in the larboratory, is valid only with in the solar system)

6. The gravitational force between two bodies does not depend upon __________.

(Their separation, Product of their masses, The sum of their masses)

7. If the radius of the earth were to shrink by 1% while its mass remaining same, the acceleration due to gravity on the earth surface would __________.

(Decrease, Remain the same, Increase)

8. Planets revolve round the sun due to __________.

(Mutual attraction and repulsion between the sun and the planets, Gravitational attraction between the sun and the planets, Centripetal Force)

9. Force of mutual attraction of earth on the objects is called __________.

(Weight, Mass, Gravitation)

10. When a person goes down to the bottom of deep mine compared to his weight on the surface then its weight will __________.

(remain same, Increase, Decrease)

11. The weight of an object at the pole is greater than at equator. This is because __________.

(Gravitational pull is more at the poles, the shape of the earth, the attraction of the moon is maximum at the earth’s surface)

12. On the surface of the moon the weight of a person __________.

(Increases, Decreases, Remains the same)

13. A spring balance is being used to weigh mass of 1kg in a lift. If the spring balance reads 9N and the acceleration of free fall (g) = 10m/s2. The lift is __________.

(Ascending at 1m/s2, At rest, Descending at 1m/s2)

14. The acceleration of free fall on moon is about one sixth of its value on earth. If on the earth a body has mass ‘m’ and weight ‘w’, then on the moon, mass and weight will be respectively about __________.

(m/6 and w/6, m/6 and w, m and w/6)

15. Spring balance is used to measure __________.

(Mass of the object, Apparent weight of the object, None of the above)

16. A person whose weight is 120 pound on the earth, on the moon his weight will be approximately __________.

(20 pound, 30 pound, 40 pound)

17. According to the law of gravitation the force of attraction between the two bodies is directly proportional to the __________.

(Sum of the masses of the bodies, Product of their masses, Difference of their masses)

18. According to the Newton’s law of gravitation the force of attraction between the two bodies is inversely proportional to the __________.

(distance between the two bodies, Square of the distance between the two bodies, none of the above)

19. The gravitational force between two bodies whose mass are m1 and m2 are placed at a distance r from each other is __________.

(,, )

20. If the distance between two masses is doubled, the gravitational force between them becomes __________.

(half of its original value, one fourth of its original value, four times of its original value)

21. The value of gravitational constant is __________.

(6.673 x 10-11 N-m2 /kg2, 7.673 x 10-11 N-m2 /kg2, 8.673 x 10-11 N-m2 /kg2)

22. The dimensions of gravitational constant are __________.

(L3M-1T-2, L2M2T-1, LM-2T-2)


23. The approximate value of the average density of the earth is __________.

(5.5 x 103 kg /m3, 6.5 x 103 kg /m3, 7.5 x 103 kg /m3)

24. The value of g varies with radius of Earth as it is __________.

(Inversely proportional to the radius of the earth, Inversely proportional to the square of the radius of the earth, Directly proportional to the square of the radius of the earth)

25. Acceleration of the moon is about __________.

(2.272 x 10-3 m/s2, 2.272 x 103 m/s2, None of these)

26. The value of orbit radius of the moon is about __________.

(3.84 x 108 m, 3.84 x 105 m, 3.84 x 103 m)

27. The time taken by the moon to complete one revolution around the earth is __________.

(2.36 x 106 seconds, 2.36 x 104 seconds, 2.36 x 108 seconds)

28. The gravitational force of attraction between two balls each of mass 100kg when they are placed at a distance of 1m apart is __________.

(6.673 x 10-8 N, 6.673 x 10-11 N, 6.673 x 10-7 N)

29. The acceleration due to gravity decreases for a point above the surface of the earth and for the same point below the surface of the earth with a __________.

(Faster rate, Slow rate, Same rate)

30. The value of the gravitational acceleration at a distance equal to the earth’s radius above the earth’s surface is __________.

(9.8 m/s2, 4.9 m/s2, 2.45 m/s2)

31. The value of the distance from the centre of the earth when the gravitational acceleration has one half the value it has on the earth’s surface __________.

(1.414 Re, 2Re, 0.5Re)

32. A person with a mass of 40kg is standing on a scale in an elevator. The elevator moves upwards with a constant acceleration of 1.2 m/s2, then the weight of the person as measured by him in the elevator is __________.

(340 N, 440N, 540N)

33. The sun exerts a force of attraction on the planets thus keeping them in their __________.

(Radii, Orbits, State of motion)

34. Numerical value of the gravitational acceleration can also be estimated by knowing the __________.

(Average Density of the Earth, Circular Motion, Mass of the earth)

35. A spring balance suspended from the ceiling of an elevator supports an object. The magnitude and direction of acceleration, which would make the balance reading zero, is __________.

(9.8 m/s2 downward, 9.8 m/s2 upward, none of these)

36. The earth traverses its circular orbit in 3.15 x 107 seconds, orbiting at an orbital velocity of 2.9 x 104 m/s, then its orbit radius is __________.

(1.45 x 1011 m, 1.45 x 108 m, 1.45 x 106 m)

37. The artificial gravity is produced in a satellite to overcome the state of weightlessness experienced by the astronaut by __________.

(Spinning it around its own axis, Increasing the orbital speed of it, Decreasing its orbital speed)

38. The expression for the frequency of rotation of the satellite to produce artificial gravity is __________.

(1/2p Ög/R, 2p Ög/R, 1/2p ÖR/g)

39. If the mass of the earth becomes four times to its initial value then the value of g will be __________.

(Equal to its initial value, Four times to its initial value, One fourth of its initial value)

40. The value of gravitation acceleration (g) on the surface of the planet of radius 105 m and mass 10kg is __________.

(6.67 x 10-8 m/s2, 6.67 x 10-11 m/s2, 6.67 x 10-10 m/s2)

41. The acceleration due to gravity on the surface of the moon is about _________.

(One sixth the acceleration due to gravity on the surface of the Earth, One fourth the acceleration due to gravity on the surface of the earth, double the acceleration due to gravity on the surface of the earth)

42. The mass of a planet and its diameter are three times those of Earth’s. Then the acceleration due to gravity on the surface of the planet will be _________.

(One third on the Earth’s, half on the Earth’s, None of the above)

43. Acceleration due to gravity at the centre of the earth is _________.

(Zero, Maximum, None of these)

44. The equation, which gives the magnitude of centripetal acceleration of the moon, is _________.

(4p2R/T2, 4pR/T2, 4p2R/T)