Momentum & Impulse — MH-CET Physics MCQs with Solutions
Free MH-CET Physics Momentum & Impulse MCQs with step-by-step solutions (21 questions). Part of Laws of Motion (Std 11). Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Momentum & Impulse · easy · theory
The linear momentum of a body is defined as:
A. The product of its mass and velocity, a vector quantity ✓ Correct
B. The product of its mass and speed, a scalar quantity
C. The product of its mass and acceleration
D. The rate of change of its velocity
Solution: It points in the same direction as the velocity.
Q2 — Momentum & Impulse · easy · theory
The SI unit of linear momentum is:
A. $\text{kg}\cdot\text{m/s}^2$
B. $\text{kg}\cdot\text{m/s}$ ✓ Correct
C. $\text{kg}\cdot\text{m}^2/\text{s}$
D. $\text{N}\cdot\text{m}$
Solution: It is equivalent to the newton second, the unit of impulse.
Q3 — Momentum & Impulse · easy · theory
Impulse is defined as:
A. The product of mass and acceleration
B. The product of force and displacement
C. The rate of change of force
D. The product of force and the time for which it acts ✓ Correct
Solution: For a variable force it is the integral $\int F\,dt$.
Q4 — Momentum & Impulse · medium · theory
The impulse-momentum theorem states that impulse equals the:
A. Work done
B. Change in momentum ✓ Correct
C. Change in velocity
D. Change in kinetic energy
Solution: It follows directly from integrating $F = \dfrac{dp}{dt}$ over time.
Q5 — Momentum & Impulse · easy · theory
The SI unit of impulse is:
A. $\text{J}$
B. $\text{N}\cdot\text{s}$ ✓ Correct
C. $\text{N}\cdot\text{m}$
D. $\text{N}/\text{s}$
Solution: This is dimensionally the same as $\text{kg}\cdot\text{m/s}$, the unit of momentum.
Q6 — Momentum & Impulse · medium · theory
A cricketer draws his hands back while catching a fast ball in order to:
A. Increase the impulse delivered
B. Reduce the change in momentum of the ball
C. Increase the time of impact and so reduce the force ✓ Correct
D. Increase the force on his hands
Solution: The change of momentum is fixed, so a longer contact time means a smaller average force.
Q7 — Momentum & Impulse · medium · theory
Airbags in a car reduce injury because they:
A. Reduce the change in momentum
B. Extend the time over which the passenger is brought to rest ✓ Correct
C. Increase the force on the passenger
D. Increase the speed of the car
Solution: Again the impulse is unchanged; only the peak force is reduced.
Q8 — Momentum & Impulse · medium · theory
The area under a force-time graph represents the:
A. Work done
B. Kinetic energy
C. Power
D. Impulse ✓ Correct
Solution: Integrating force over time gives the impulse, and hence the momentum change.
Q9 — Momentum & Impulse · medium · theory
For a body of constant mass, force is related to momentum by:
A. $F = \dfrac{dp}{dx}$
B. $F = \dfrac{p}{t^2}$
C. $F = \dfrac{dp}{dt}$ ✓ Correct
D. $F = pt$
Solution: This is the fundamental statement of the second law.
Q10 — Momentum & Impulse · easy · numerical
A body of mass $2\text{ kg}$ moves at $5\text{ m/s}$. Its momentum is:
A. $7\text{ kg}\cdot\text{m/s}$
B. $2.5\text{ kg}\cdot\text{m/s}$
C. $10\text{ kg}\cdot\text{m/s}$ ✓ Correct
D. $25\text{ kg}\cdot\text{m/s}$
Solution: $p = mv = 2 \times 5 = 10\text{ kg}\cdot\text{m/s}$.
Q11 — Momentum & Impulse · hard · numerical
A ball of mass $0.2\text{ kg}$ strikes a wall at $15\text{ m/s}$ and rebounds elastically with the same speed. The impulse on the ball is:
A. $1.5\text{ N}\cdot\text{s}$
B. $Zero$
C. $6\text{ N}\cdot\text{s}$ ✓ Correct
D. $3\text{ N}\cdot\text{s}$
Solution: The velocity reverses, so $J = m(v - (-v)) = 2mv = 2 \times 0.2 \times 15 = 6\text{ N}\cdot\text{s}$.
Q12 — Momentum & Impulse · hard · numerical
For the ball of the previous type ($6\text{ N}\cdot\text{s}$ impulse) with a contact time of $0.02\text{ s}$, the average force is:
A. $300\text{ N}$ ✓ Correct
B. $600\text{ N}$
C. $0.12\text{ N}$
D. $150\text{ N}$
Solution: $F = \dfrac{J}{\Delta t} = \dfrac{6}{0.02} = 300\text{ N}$.
Q13 — Momentum & Impulse · easy · numerical
A force of $20\text{ N}$ acts for $3\text{ s}$. The impulse delivered is:
A. $180\text{ N}\cdot\text{s}$
B. $6.67\text{ N}\cdot\text{s}$
C. $60\text{ N}\cdot\text{s}$ ✓ Correct
D. $23\text{ N}\cdot\text{s}$
Solution: $J = F\Delta t = 20 \times 3 = 60\text{ N}\cdot\text{s}$.
Q14 — Momentum & Impulse · easy · numerical
A body of mass $5\text{ kg}$ has its velocity changed by $4\text{ m/s}$. The change in its momentum is:
A. $0.8\text{ kg}\cdot\text{m/s}$
B. $20\text{ kg}\cdot\text{m/s}$ ✓ Correct
C. $1.25\text{ kg}\cdot\text{m/s}$
D. $9\text{ kg}\cdot\text{m/s}$
Solution: $\Delta p = m\Delta v = 5 \times 4 = 20\text{ kg}\cdot\text{m/s}$.
Q15 — Momentum & Impulse · easy · numerical
A momentum change of $10\text{ kg}\cdot\text{m/s}$ occurs in $2\text{ s}$. The average force is:
A. $5\text{ N}$ ✓ Correct
B. $12\text{ N}$
C. $0.2\text{ N}$
D. $20\text{ N}$
Solution: $F = \dfrac{\Delta p}{\Delta t} = \dfrac{10}{2} = 5\text{ N}$.
Q16 — Momentum & Impulse · medium · numerical
If the momentum of a body is doubled, its kinetic energy becomes:
A. Twice as large
B. Half as large
C. Unchanged
D. Four times as large ✓ Correct
Solution: $K = \dfrac{p^2}{2m} \propto p^2$.
Q17 — Momentum & Impulse · easy · numerical
A body of mass $0.1\text{ kg}$ moves at $20\text{ m/s}$. Its momentum is:
A. $20.1\text{ kg}\cdot\text{m/s}$
B. $2\text{ kg}\cdot\text{m/s}$ ✓ Correct
C. $0.005\text{ kg}\cdot\text{m/s}$
D. $200\text{ kg}\cdot\text{m/s}$
Solution: $p = 0.1 \times 20 = 2\text{ kg}\cdot\text{m/s}$.
Q18 — Momentum & Impulse · medium · numerical
A bullet of mass $20\text{ g}$ travels at $400\text{ m/s}$. Its momentum is:
A. $8\text{ kg}\cdot\text{m/s}$ ✓ Correct
B. $80\text{ kg}\cdot\text{m/s}$
C. $0.05\text{ kg}\cdot\text{m/s}$
D. $8000\text{ kg}\cdot\text{m/s}$
Solution: $p = 0.02 \times 400 = 8\text{ kg}\cdot\text{m/s}$.
Q19 — Momentum & Impulse · hard · numerical
The bullet of the previous type ($8\text{ kg}\cdot\text{m/s}$) is stopped in $0.01\text{ s}$. The average force on it is:
A. $8000\text{ N}$
B. $800\text{ N}$ ✓ Correct
C. $80\text{ N}$
D. $0.08\text{ N}$
Solution: $F = \dfrac{8}{0.01} = 800\text{ N}$.
Q20 — Momentum & Impulse · hard · numerical
A constant force of $5\text{ N}$ acts for $4\text{ s}$ on a body of mass $2\text{ kg}$ initially at rest. Its final velocity is:
A. $40\text{ m/s}$
B. $20\text{ m/s}$
C. $2.5\text{ m/s}$
D. $10\text{ m/s}$ ✓ Correct
Solution: Impulse $= 20\text{ N}\cdot\text{s} = m\Delta v$, so $\Delta v = \dfrac{20}{2} = 10\text{ m/s}$.
Q21 — Momentum & Impulse · hard · numerical
Two bodies of masses $2\text{ kg}$ and $4\text{ kg}$ have equal momenta. The ratio of their kinetic energies is:
A. $2 : 1$ ✓ Correct
B. $4 : 1$
C. $1 : 2$
D. $1 : 1$
Solution: With $p$ equal, $K = \dfrac{p^2}{2m} \propto \dfrac{1}{m}$, so the lighter body has more kinetic energy.