## MCQ Questions for Class 9 Science: Ch 10 Gravitation 1. The earth and the moon are attracted to each other by gravitational force. The earth attracts the moon with a force that is:
(a) More than that exerted by the moon
(b) Same as that exerted by the moon
(c) Less than that exerted by the moon
(d) Not related to that exerted by the moon
► (b) Same as that exerted by the moon

2. An apple and a stone dropped from certain height accelerates
(a) equally
(b) differently
(c) depending on density
(d) depends on the position of the Sun
► (a) equally

3. According to Archimedes’ principle when a body is submerged in a liquid, its apparent weight
(a) decreases
(b) increases
(c) remains unchanged
(d) may increase or decrease depending upon the material of the body
► (a) decreases

4. If upthrust U is equal to 1/4  the weight of the object in air, then the weight felt in the liquid is
(a) 1/4W
(b) 3/4W
(c) 1/2W
(d) 2 W
► (b) 3/4W

5. A mass weighing W can float if the upthrust U is related as
(a) U > W
(b) U = W
(c) U < W
(d) U ≥ W
► (a) U > W

6. The pressure exerted by man on earth is minimum when he
(a) sits
(b) stands on one foot
(c) stands on both feet
(d) lies on ground
► (d) lies on ground

7. When a body floats in a liquid, its apparent weight is always
(a) less than the weight of the body
(b) more than the weight of the body
(c) equal to the weight of the body
(d) zero
► (d) zero

8. Thrust exerted by an iron cuboid when placed on sand is equal to
(a) mass of cuboid
(b) mass per unit surface area
(c) weight of cuboid
(d) weight per unit surface area
► (c) weight of cuboid

9. The gravitational force between two bodies does not depend on
(a) their separation
(b) their masses
(c) the product of their masses
(d) the medium between the two bodies
► (d) the medium between the two bodies

10. Two objects of different masses falling freely near the surface of moon would
(a) have same velocities of any instant
(b) have different accelerations
(c) experience forces of different magnitudes
(d) undergo a change in their inertia
► (c) experience forces of different magnitudes

11. School bags have a broader base to reduce
(a) pressure
(b) weight
(c) air resistance
(d) normal reaction
► (a) pressure

12. Inverse square law means F α?
(a) 1/r
(b) 1/r2
(c) 1/r4
(d) 1/r3
► (b) 1/r2

13. When a body is weighed in a liquid, the loss in weight is equal to
(a) weight of liquid displaced by the body
(b) weight of water displaced by the body
(c) weight of body in air
(d) half the weight of body in air
► (a) weight of liquid displaced by the body

14. The constant G
(a) is a very small quantity
(b) is a force
(c) is the same as g
(d) decrease with increasing altitude
► (a) is a very small quantity

15. The mass of the body on the moon is 40kg, what is the weight on the earth.
(a) 240kg
(b) 392N
(c) 240N
(d) 400kg
► (b) 392N

16. The weight of an object is least at some region of the earth. What will be the colour of bears found in that region.
(a) black
(b) white
(c) blue
(d) brown
► (b) white

17. Acceleration due to gravity varies with
(a) height
(b) depth
(c) shape of the planet
(d) all of these
► (d) all of these

18. The relative density of a solid is 0.6. It floats in water with
(a) 40% of its volume inside water
(b) 60% of its volume inside water
(c) whole of its volume inside water
(d) any fraction of its volume inside water
► (b) 60% of its volume inside water

19. The walls of a dam at the bottom are made thick because
(a) it looks attractive
(b) it is conventional
(c) it is convenient
(d) water exerts large pressure at the bottom
► (d) water exerts large pressure at the bottom

20. Two particles are placed at some distance. If the mass of each of the two particles is doubled, keeping the distance between them unchanged, the value of gravitational force between them will be
(a) 1/4 times
(b) 4 times
(c) 1/2 times
(d) unchanged
► (b) 4 times

21. An empty closed drum and a filled drum of same dimension will bring
(a) same upthrust
(b) same volume
(c) both (a) and (b)
(d) neither (a) nor (b)
► (c) both (a) and (b)

22. What is buoyant force-
(a) An upward force on an object immersed in a liquid
(b) Partially downward force
(c) A down ward force on an object immersed in a liquid
(d) None of the above.
► (a) An upward force on an object immersed in a liquid

23. A rectangular block of wood of dimensions 40cm x 20cm x 10cm is kept on a table top. The pressure is greatest when it is rested on
(a) equal for all cases
(b) 20cm x 10 cm
(c) 40cm x 10cm
(d) 40cm x 20cm
► (b) 20cm x 10 cm

24. Gravitation force is a
(a) short range force
(b) non-central force
(c) weakest force
(d) strongest force
► (c) weakest force

25. “The equation of motion for free fall can be used in case of any free fall” is
(a) partially true
(b) partially false.
(c) true
(d) false
► (b) partially false.

26. If the radius of earth were to shrink by 1%, its mass remaining the same, the acceleration due to gravity on earth’s surface would
(a) decrease
(b) increase
(c) remain unchanged
(d) can't be calculated
► (b) increase

27. A sharp edge blade is more effective in cutting than a blunt blade due to
(a) Low force
(b) Low pressure
(c) Large contact area
(d) Small contact area
► (d) Small contact area

28. An object weighs 10 N in air. When immersed fully in water, it weighs only 8 N. The weight of the liquid displaced by the object will be
(a) 2 N
(b) 8 N
(c) 10 N
(d) 12 N
► (a) 2 N

29. The neck and bottom of a bottle are 2cm and 20 cm in diameter respectively. The cork is pressed with same pressure. If the cork is pressed with a force of 1.2 kgf on the neck of the bottle, the force exerted on the bottom of the bottle will be
(a) 1200 kgf
(b) 120 kgf
(c) 1.2 kgf
(d) 12 kgf
► (b) 120 kgf

30. Weight of 1 kg is
(a) 9.8 newton
(b) 1 kg-wt
(c) both (a) and (b)
(d) either (a) or (b)
► (a) 9.8 newton

31. Archimedes’ principle holds for
(a) liquids only
(b) gases only
(c) liquids and gases both
(d) neither liquids nor gases
► (c) liquids and gases both

32. An apple falls from a tree because of gravitational attraction between the earth and apple. If F1 is the magnitude of force exerted by the earth on the apple and F1 is the magnitude of force exerted by apple on earth, then
(a) F1 is very much greater than F1
(b) F1 is very much greater than F1
(c) F1 is only a little greater than F1
(d) F1 and F1 are equal
► (d) F1 and F1 are equal

33. Freely falling objects weight ._______.
(a) zero
(b) 1/4 time
(c) 1/2 time
(d) unchanged
► (a) zero

34. For a given applied thrust, pressure exerted on a surface by a sharp pin is
(a) more than the pressure exerted by a blunt pin.
(b) less than the pressure exerted by a blunt pin.
(c) equal to the pressure exerted by a blunt pin.
(d) either less or equal to the pressure exerted by a blunt pin.
► (a) more than the pressure exerted by a blunt pin.