Inertia — Homi Bhabha Class 9 Physics MCQs with Solutions
Free Homi Bhabha Class 9 Physics Inertia MCQs with step-by-step solutions (10 questions). Part of Laws of Motion & Force. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Inertia · medium · theory
The inertia of a body depends on its:
A. mass ✓ Correct
B. acceleration
C. velocity
D. shape
Solution: Inertia is the tendency to resist a change in the state of motion, and it is measured by (and increases with) mass.
Q2 — Inertia · medium · theory
Dust particles are removed when a carpet is beaten with a stick. This is due to:
A. inertia of rest ✓ Correct
B. friction
C. inertia of direction
D. inertia of motion
Solution: Beating sets the carpet in motion while the dust, by inertia of rest, tends to stay in place and so separates.
Q3 — Inertia · hard · theory
Which of the following bodies, moving at the same speed, has the greatest inertia?
A. A bicycle
B. A car
C. A football
D. A loaded truck ✓ Correct
Solution: Inertia increases with mass; the loaded truck has the largest mass and hence the greatest inertia.
Q4 — Inertia · medium · theory
When a playing card on a glass is flicked sharply, the coin on it drops into the glass. This illustrates:
A. conservation of energy
B. inertia of motion
C. inertia of rest ✓ Correct
D. Newton's third law
Solution: The card moves out quickly, but the coin, by inertia of rest, stays and falls into the glass.
Q5 — Inertia · medium · theory
A passenger in a car falls sideways when the car takes a sharp turn. This is due to:
A. gravity
B. inertia of direction ✓ Correct
C. inertia of motion
D. inertia of rest
Solution: The body tends to keep moving in its original straight-line direction, i.e. inertia of direction.
Q6 — Inertia · hard · theory
Assertion (A): A heavy stone is harder to start moving than a light ball. Reason (R): Greater mass means greater inertia.
A. A is false but R is true
B. Both A and R are true but R is NOT the correct explanation of A
C. A is true but R is false
D. Both A and R are true and R is the correct explanation of A ✓ Correct
Solution: More mass means more inertia, so more force is needed to change its state of rest — R correctly explains A.
Q7 — Inertia · easy · theory
The inertia of a body depends only on its:
A. mass ✓ Correct
B. colour
C. shape
D. speed
Solution: Inertia is the resistance to a change in the state of motion and is measured by mass; it does not depend on speed, shape or colour.
Q8 — Inertia · easy · theory
When a bus at rest suddenly starts moving forward, the passengers tend to fall backward. This is due to:
A. inertia of motion
B. inertia of direction
C. friction between feet and floor
D. inertia of rest ✓ Correct
Solution: The lower body moves with the bus while the upper body, by inertia of rest, tends to stay in place, so the passenger falls backward.
Q9 — Inertia · medium · theory
An iron ball and a wooden ball have exactly the same size, but the iron ball is much harder to set in motion. This is because the iron ball has:
A. greater volume
B. greater inertia due to greater mass ✓ Correct
C. greater friction with air
D. greater acceleration
Solution: Both balls are the same size, but iron is denser and so has more mass; greater mass means greater inertia and more force is needed to move it.
Q10 — Inertia · hard · theory
Assertion (A): A body of larger mass needs a larger force to give it the same acceleration as a lighter body. Reason (R): The inertia of a body is directly proportional to its mass.
A. A is false but R is true
B. A is true but R is false
C. Both A and R are true but R is NOT the correct explanation of A
D. Both A and R are true and R is the correct explanation of A ✓ Correct
Solution: From F = ma, a fixed acceleration needs force proportional to mass, and mass is the measure of inertia; so R (inertia is proportional to mass) correctly explains A.