⚡ Force and Laws of Motion – Class 9 Science MCQs

Section 1: Concept of Force & Newton’s First Law (Q1–Q25)

Q1. Force can change:

A. Shape of an object
B. Speed of an object
C. Direction of motion
D. All of the above

✅ Correct Answer: D. All of the above

Explanation:

• A. Correct but limited.
• B. Correct but limited.
• C. Correct but limited.
• D. Correct, force can change shape, speed, or direction.

Q2. The SI unit of force is:

A. Joule
B. Newton
C. Watt
D. Pascal

✅ Correct Answer: B. Newton

Explanation:

• A. Joule = energy.
• B. Correct, 1 Newton = force causing 1 kg mass to accelerate 1 m/s².
• C. Watt = power.
• D. Pascal = pressure.

Q3. According to Newton’s first law, an object continues in its state of rest or motion unless:

A. Mass changes
B. Force is applied
C. Time increases
D. Momentum is zero

✅ Correct Answer: B. Force is applied

Explanation:

• A. Mass doesn’t change state.
• B. Correct, external force is required.
• C. Time has no effect.
• D. Momentum may be non-zero.

Q4. Newton’s first law is also called law of:

A. Momentum
B. Acceleration
C. Inertia
D. Force

✅ Correct Answer: C. Inertia

Explanation:

• A, B, D. Not correct.
• C. Correct, tendency to resist change is inertia.

Q5. Which of the following is the best example of inertia of rest?

A. Passenger moves forward when car stops suddenly
B. Mud flying off tyre
C. Rider thrown backward when horse gallops
D. Athletes running before long jump

✅ Correct Answer: A. Passenger moves forward when car stops suddenly

Explanation:

• A. Correct, body at rest tends to stay at rest.
• B. Inertia of direction.
• C. Inertia of motion.
• D. Technique, not example.

Q6. Which of the following shows inertia of motion?

A. Book on table remains at rest
B. Person falls backward when bus starts suddenly
C. Coin remains on card when card is flicked
D. A bullet fired from gun

✅ Correct Answer: B. Person falls backward when bus starts suddenly

Explanation:

• A. Inertia of rest.
• B. Correct, passenger tends to remain in rest when bus moves.
• C. Inertia of rest.
• D. Example of force, not inertia.

Q7. Inertia depends on:

A. Velocity of body
B. Acceleration of body
C. Mass of body
D. Shape of body

✅ Correct Answer: C. Mass of body

Explanation:

• A, B, D. Not correct.
• C. Correct, larger mass → larger inertia.

Q8. Which has greater inertia?

A. Bicycle
B. Car
C. Bus
D. Train

✅ Correct Answer: D. Train

Explanation:

• Greater mass = greater inertia → Train > Bus > Car > Cycle.

Q9. An athlete runs before taking a long jump to:

A. Increase acceleration
B. Decrease inertia
C. Gain momentum
D. Reduce displacement

✅ Correct Answer: C. Gain momentum

Explanation:

• A. Not useful.
• B. Inertia cannot change.
• C. Correct, running increases momentum, helps in jump.
• D. Wrong.

Q10. Example of inertia of direction is:

A. Passenger moves forward when car stops
B. A stone tied to a string moves in circular path and flies tangentially if string breaks
C. Book remains at rest on table
D. Dust comes out when carpet is beaten

✅ Correct Answer: B. A stone tied to a string moves tangentially if string breaks

Q11. Newton’s first law gives concept of:

A. Force
B. Momentum
C. Inertia
D. Acceleration

✅ Correct Answer: C. Inertia

Q12. The property of a body by which it resists change in state is:

A. Acceleration
B. Inertia
C. Force
D. Momentum

✅ Correct Answer: B. Inertia

Q13. A coin on a card falls into glass when card is flicked. This shows:

A. Inertia of motion
B. Inertia of direction
C. Inertia of rest
D. None

✅ Correct Answer: C. Inertia of rest

Q14. A body of mass 10 kg has more inertia than a body of:

A. 1 kg
B. 5 kg
C. 8 kg
D. All of these

✅ Correct Answer: D. All of these

Q15. If no force acts on a moving body, it will:

A. Stop
B. Move with constant velocity
C. Accelerate
D. Change direction

✅ Correct Answer: B. Move with constant velocity

Q16. A man jumps from moving bus and falls forward. This is due to:

A. Inertia of motion
B. Inertia of rest
C. Inertia of direction
D. Gravitational pull

✅ Correct Answer: A. Inertia of motion

Q17. SI unit of momentum is:

A. kg m/s
B. N m
C. Joule
D. Watt

✅ Correct Answer: A. kg m/s

Q18. A cricket player lowers his hands while catching ball to:

A. Increase acceleration
B. Increase time of contact
C. Decrease time of contact
D. Reduce distance

✅ Correct Answer: B. Increase time of contact

Explanation:

• Increases time → reduces force (F = Δp/Δt).

Q19. A passenger standing in bus is thrown forward when bus stops due to:

A. Inertia of motion
B. Inertia of rest
C. Inertia of direction
D. Friction

✅ Correct Answer: A. Inertia of motion

Q20. Tendency of passengers to fall sideways when bus takes turn is due to:

A. Inertia of direction
B. Inertia of rest
C. Inertia of motion
D. Acceleration

✅ Correct Answer: A. Inertia of direction

Q21. Who gave three laws of motion?

A. Galileo
B. Newton
C. Einstein
D. Faraday

✅ Correct Answer: B. Newton

Q22. Newton’s first law was first suggested by:

A. Galileo
B. Newton
C. Kepler
D. Copernicus

✅ Correct Answer: A. Galileo

Q23. The force required to stop a moving body depends on its:

A. Speed
B. Acceleration
C. Momentum
D. Time

✅ Correct Answer: C. Momentum

Q24. The inertia of an object is measured by its:

A. Force
B. Mass
C. Acceleration
D. Weight

✅ Correct Answer: B. Mass

Q25. A person jumping out of a moving train may fall with his head forward because of:

A. Inertia of direction
B. Inertia of rest
C. Inertia of motion
D. Acceleration

✅ Correct Answer: C. Inertia of motion

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