Class 8 Science – How Force Affects Motion
20 MCQs
1. What can a force do to a moving object?
A. Only stop it
B. Only speed it up
C. Change its speed or direction
D. Nothing
2. A force can change the ______ of a moving object.
A. Colour
B. Direction
C. Mass
D. Temperature
3. When a force acts in the direction of motion, the speed of an object generally:
A. Decreases
B. Increases
C. Becomes zero
D. Remains unchanged
4. When a force acts opposite to the direction of motion, the object generally:
A. Speeds up
B. Slows down
C. Changes its mass
D. Becomes heavier
5. A football at rest starts moving when it is kicked. This shows that force can:
A. Change colour
B. Produce motion
C. Change mass
D. Produce light
6. A moving bicycle stops when brakes are applied because the force of friction:
A. Increases its speed
B. Opposes its motion
C. Changes its mass
D. Pulls it upward
7. Which force acts to slow down a moving object?
A. Frictional force
B. Magnetic force
C. Muscular force
D. Buoyant force
8. A batsman hits a moving cricket ball. The force exerted by the bat can change the ball's:
A. Speed and direction
B. Mass only
C. Colour only
D. Temperature only
9. A goalkeeper catches a fast-moving football. The force applied by the goalkeeper:
A. Stops the ball
B. Increases its speed
C. Changes its mass
D. Produces electricity
10. Which situation is an example of force changing the direction of motion?
A. Pushing a stationary box
B. Hitting a moving ball with a bat
C. Lifting a bag
D. Compressing a sponge
11. The SI unit of force is:
A. Joule
B. Pascal
C. Newton
D. Watt
12. A force can change the motion of an object by changing its:
A. Speed
B. Direction
C. Both A and B
D. Colour
13. A stationary toy car starts moving when pushed. The push is a:
A. Force
B. Pressure
C. Mass
D. Energy
14. If two forces act on an object in opposite directions with equal magnitude, the net force is:
A. Maximum
B. Zero
C. Double
D. Half
15. If two forces act in the same direction, the net force is:
A. Their sum
B. Their difference
C. Always zero
D. Always one newton
16. A force of 10 N acts on an object towards the right and another force of 6 N acts towards the left. The net force is:
A. 16 N left
B. 16 N right
C. 4 N right
D. 4 N left
17. Which of the following can change the speed of a moving object?
A. Force
B. Colour
C. Shape only
D. Volume only
18. A cyclist applies brakes while moving downhill. The bicycle slows down mainly due to:
A. Frictional force
B. Magnetic force
C. Gravitational force disappearing
D. Muscular force
19. When a force changes the direction of a moving object, the object:
A. Must stop
B. Continues moving in a different direction
C. Loses all its mass
D. Becomes stationary permanently
20. Which statement is correct about force?
A. Force can never change motion.
B. Force ca
n change the speed or direction of an object.
C. Force can change only the colour of an object.
D. Force has no effect on moving objects.
Answer Key – Class 8: How Force Affects Motion
Q. Ans. Q. Ans.
1 C 11 C
2 B 12 C
3 B 13 A
4 B 14 B
5 B 15 A
6 B. 16 C
7 A 17 A
8 A 18 A
9 A 19 B
10 B 20 B
Class 9 – Force and Laws of Motion
1. A car of mass 1000 kg starts from rest and attains a velocity of 20 m/s in 10 s with uniform acceleration. Calculate:
(a) acceleration of the car
(b) force acting on the car.
2. A force of 500 N acts on a body of mass 100 kg, initially at rest. Calculate:
(a) acceleration produced
(b) velocity acquired by the body in 8 s.
3. A truck of mass 2000 kg is moving with a velocity of 10 m/s. A force of 4000 N acts on it in the direction of motion for 5 s. Calculate:
(a) acceleration produced
(b) final velocity of the truck.
4. A body of mass 5 kg moving with a velocity of 4 m/s is accelerated uniformly to 14 m/s in 5 s. Calculate:
(a) acceleration
(b) force required to produce this acceleration.
5. A car of mass 1500 kg moving at 20 m/s is brought to rest in 10 s by applying brakes. Calculate:
(a) retardation
(b) braking force acting on the car.