Class 9 Science – How Forces Affect Motion
1. A moving bus suddenly stops, and passengers
move forward. Which concept best explains this
observation?
A. Inertia of rest
B. Inertia of motion
C. Newton’s third law
D. Gravitational force
2. Two forces of 20 N and 15 N act on a box in
opposite directions. What will be the net force?
A. 35 N in the direction of 20 N
B. 5 N in the direction of 20 N
C. 5 N in the direction of 15 N
D. 0 N
3. A 5 kg object is acted upon by a net force
of 20 N. If the force is increased to 40 N without
changing its mass, what happens to its acceleration?
A. It becomes half
B. It remains unchanged
C. It becomes double
D. It becomes four times
4. A heavy truck and a small car are moving
at the same velocity. Which has greater momentum?
A. Car
B. Truck
C. Both have equal momentum
D. Cannot be determined
5. A student pushes a wall with a force of 100 N,
but the wall does not move. Which statement is
correct?
A. No force is applied by the student
B. The wall applies an equal and opposite force
on the student
C. The wall applies no force
D. Newton’s third law does not apply
6. A football is initially at rest. A player kicks it
and it starts moving. What caused the change
in its state of motion?
A. Balanced force
B. Unbalanced force
C. Inertia
D. Momentum only
7. A 2 kg object accelerates at 3 m/s². Another
object of mass 6 kg experiences the same force.
What will be its acceleration?
A. 0.5 m/s²
B. 1 m/s²
C. 3 m/s²
D. 9 m/s²
8. A book is lying on a horizontal table.
The gravitational force on the book is balanced
by the:
A. Frictional force
B. Muscular force
C. Normal force of the table
D. Magnetic force
9. A cyclist stops pedalling but the bicycle
continues moving for some distance before
stopping. Which force mainly causes it to slow
down?
A. Magnetic force
B. Frictional force
C. Muscular force
D. Electrostatic force
10. A person jumps from a boat onto the shore,
and the boat moves backward. If the person
jumps with greater speed, the backward motion
of the boat is likely to:
A. Decrease
B. Increase
C. Become zero
D. Remain exactly the same
11. A force of 30 N acts on a 10 kg body. Another
force of 10 N acts in the opposite direction.
What is the acceleration of the body?
A. 1 m/s²
B. 2 m/s²
C. 3 m/s²
D. 4 m/s²
12. Two objects have the same momentum.
Object A has a mass of 2 kg and Object B has
a mass of 4 kg. Which object has greater velocity?
A. Object A
B. Object B
C. Both have equal velocity
D. Cannot be determined
13. A cricket player moves his hands backward
while catching a fast-moving ball. The main
purpose is to:
A. Increase the force on his hands
B. Increase the time of impact and reduce the force
C. Increase the momentum of the ball
D. Stop the ball without applying force
14. A passenger in a car moves sideways when
the car takes a sharp turn. This is mainly due to:
A. Inertia of direction
B. Inertia of rest
C. Gravitational force
D. Friction only
15. A 4 kg object is moving with an acceleration
of 5 m/s². If its mass becomes 8 kg while the same
force continues to act, the new acceleration will be:
A. 10 m/s²
B. 5 m/s²
C. 2.5 m/s²
D. 1.25 m/s²
16. A rocket moves upward because gases are
expelled downward at high speed. This is an
application of:
A. Newton’s first law
B. Newton’s second law only
C. Newton’s third law
D. Law of conservation of mass only
17. A loaded trolley is harder to accelerate than
an empty trolley when the same force is applied.
The best explanation is that the loaded trolley has:
A. Less inertia
B. Greater inertia
C. Less mass
D. Greater acceleration
18. Two students push a box from opposite sides.
Student A applies 50 N eastward and Student B
applies 50 N westward. The box remains at rest.
If Student B reduces the force to 30 N, the box will:
A. Remain at rest
B. Move westward
C. Move eastward
D. Move vertically upward
19. A 10 kg object moving at 2 m/s has the same
momentum as another object moving at 5 m/s.
What is the mass of the second object?
A. 2 kg
B. 4 kg
C. 5 kg
D. 25 kg
20. A person standing in a bus throws a ball vertically upward.
If the bus is moving with constant velocity, where wi
ll the ball land relative to the person?
A. Behind the person
B. In front of the person
C. Back in the person’s hand
D. Outside the bus
Class 9 Science – How Forces Affect Motion
HOTS MCQs – Answer Key
1. B. Inertia of motion
2. B. 5 N in the direction of 20 N
3. C. It becomes double
4. B. Truck
5. B. The wall applies an equal and opposite force on the student
6. B. Unbalanced force
7. B. 1 m/s²
8. C. Normal force of the table
9. B. Frictional force
10. B. Increase
11. B. 2 m/s²
12. A. Object A
13. B. Increase the time of impact and reduce the force
14. A. Inertia of direction
15. C. 2.5 m/s²
16. C. Newton’s third law
17. B. Greater inertia
18. C. Move east
ward
19. B. 4 kg
20. C. Back in the person’s hand