Force and Laws of Motion Class 9 MCQs with Answers
Force and Laws of Motion Class 9 MCQs with Answers
Class: CBSE Class 9
Subject: Science
Section: Physics
Topic: Force and Laws of Motion
These Multiple Choice Questions (MCQs) are designed strictly as per the NCERT syllabus, making them ideal for CBSE Class 9 Science Board Examinations preparation.
Subject: Science
Section: Physics
Topic: Force and Laws of Motion
These Multiple Choice Questions (MCQs) are designed strictly as per the NCERT syllabus, making them ideal for CBSE Class 9 Science Board Examinations preparation.
1. Force is defined as:
Answer: A
Force is a push or pull acting on an object that can change its state of motion or shape.
2. SI unit of force:
Answer: B
Force = mass × acceleration. Unit → Newton (N).
3. First law of motion is also called:
Answer: A
It states that objects resist change in their state of motion — inertia.
4. Inertia depends on:
Answer: B
Greater mass → greater inertia → more resistance to motion change.
5. Second law gives relation between:
Answer: B
F = ma — fundamental relation of motion dynamics.
6. Unit of momentum:
Answer: A
Momentum = mass × velocity → kg m/s.
7. Momentum is a:
Answer: B
It has both magnitude and direction.
8. Third law states:
Answer: B
Action and reaction forces act on different bodies.
9. Example of third law:
Answer: A
We push ground backward; ground pushes us forward.
10. Rate of change of momentum gives:
Answer: C
This is mathematical form of second law.
11. Conservation of momentum applies in:
Answer: A
No external force → total momentum constant.
12. If force doubles, acceleration:
Answer: B
From F = ma, a ∝ F.
13. A truck and car have same velocity. Which has more momentum?
Answer: B
Momentum depends on mass; truck heavier.
14. Balanced forces cause:
Answer: C
Net force zero → no acceleration.
15. Unbalanced force causes:
Answer: B
Net force ≠ 0 → motion change.
16. Rocket works on:
Answer: C
Gases expelled backward → rocket forward.
17. If mass increases, acceleration:
Answer: B
a = F/m → inverse relation.
18. Force needed to stop moving object depends on:
Answer: A
Greater momentum → greater stopping force.
19. Impulse equals:
Answer: A
Impulse = Change in momentum.
20. Catching a ball with moving hands reduces injury because:
Answer: A
Increasing stopping time reduces force (Impulse concept).