Acceleration — Homi Bhabha Class 9 Physics MCQs with Solutions
Free Homi Bhabha Class 9 Physics Acceleration MCQs with step-by-step solutions (10 questions). Part of Motion & Kinematics. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Acceleration · medium · numerical
A car's velocity increases uniformly from 5 m/s to 25 m/s in 4 s. Its acceleration is:
A. 6.25 m/s²
B. 20 m/s²
C. 7.5 m/s²
D. 5 m/s² ✓ Correct
Solution: $a = \dfrac{v - u}{t} = \dfrac{25 - 5}{4} = 5$ m/s².
Q2 — Acceleration · hard · numerical
A car moving at 90 km/h is brought to rest in 5 s. Its retardation is:
A. 25 m/s²
B. 4.5 m/s²
C. 18 m/s²
D. 5 m/s² ✓ Correct
Solution: Convert: $90$ km/h $= 25$ m/s; retardation $= \dfrac{25}{5} = 5$ m/s² (18 m/s² comes from forgetting to convert km/h).
Q3 — Acceleration · medium · theory
When the acceleration of a body acts opposite to its direction of motion, the body:
A. moves with uniform velocity
B. slows down (retardation) ✓ Correct
C. stops instantly
D. speeds up
Solution: Acceleration opposite to motion reduces the speed — this is retardation (negative acceleration).
Q4 — Acceleration · medium · numerical
A body is dropped from rest. Taking $g = 10$ m/s², its velocity after 3 s of free fall is:
A. 30 m/s ✓ Correct
B. 10 m/s
C. 3.3 m/s
D. 90 m/s
Solution: $v = u + gt = 0 + 10 \times 3 = 30$ m/s.
Q5 — Acceleration · hard · theory
Assertion (A): A body thrown vertically upward has zero velocity but non-zero acceleration at its highest point. Reason (R): At the highest point gravity still acts on the body.
A. A is true but R is false
B. A is false but R is true
C. Both A and R are true and R is the correct explanation of A ✓ Correct
D. Both A and R are true but R is NOT the correct explanation of A
Solution: At the top $v = 0$, but gravity ($g$) still acts downward, so acceleration is non-zero — R correctly explains A.
Q6 — Acceleration · hard · numerical
On a velocity–time graph, a straight line rises from 0 to 20 m/s in 4 s. The acceleration represented is:
A. 80 m/s²
B. 0.2 m/s²
C. 5 m/s² ✓ Correct
D. 4 m/s²
Solution: On a v–t graph, acceleration = slope $= \dfrac{20 - 0}{4} = 5$ m/s².
Q7 — Acceleration · easy · theory
Acceleration is defined as the rate of change of:
A. Speed only
B. Velocity ✓ Correct
C. Displacement
D. Distance
Solution: Acceleration = change in velocity divided by time taken. Because velocity is a vector, acceleration is a vector too.
Q8 — Acceleration · medium · numerical
A car speeds up uniformly from 10 m/s to 30 m/s in 5 s. What is its acceleration?
A. 4 m/s squared ✓ Correct
B. 2 m/s squared
C. 8 m/s squared
D. 40 m/s squared
Solution: Acceleration = (final velocity minus initial velocity) divided by time = (30 minus 10) divided by 5 = 20 divided by 5 = 4 m/s squared.
Q9 — Acceleration · medium · numerical
A bus moving at 20 m/s is brought to rest uniformly in 4 s. What is its acceleration?
A. 5 m/s squared
B. 80 m/s squared
C. minus 5 m/s squared ✓ Correct
D. minus 4 m/s squared
Solution: Acceleration = (0 minus 20) divided by 4 = minus 5 m/s squared. The negative sign shows it is a retardation, since the bus is slowing down.
Q10 — Acceleration · hard · theory
A ball is thrown vertically upward. At the highest point of its path, which statement is correct?
A. Both its velocity and acceleration are zero
B. Both velocity and acceleration point upward
C. Its velocity is zero but its acceleration is not zero ✓ Correct
D. Its acceleration is zero but its velocity is not zero
Solution: At the top the ball stops for an instant, so its velocity is zero. But gravity still acts, so the acceleration is g pointing downward, about 9.8 m/s squared. It never becomes zero during the flight.