Conservation of Linear Momentum — NEET Physics MCQs with Solutions
Free NEET Physics Conservation of Linear Momentum MCQs with step-by-step solutions (8 questions). Part of Centre of Mass, Momentum & Collisions. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Conservation of Linear Momentum · easy · theory
The total linear momentum of a system is conserved when:
A. Kinetic energy is conserved
B. The net external force on the system is zero ✓ Correct
C. The bodies are rigid
D. Gravity is absent
Solution: dP⃗/dt = F⃗_ext; zero net external force ⇒ P⃗ constant, whatever the internal forces (collisions, explosions).
Q2 — Conservation of Linear Momentum · medium · theory
A bomb at rest explodes into fragments. Immediately afterwards, the vector sum of the momenta of all fragments is:
A. Zero ✓ Correct
B. Equal to the energy released
C. Directed upward
D. Random
Solution: The explosion is internal: total momentum stays what it was — zero. (Kinetic energy, of course, increases.)
Q3 — Conservation of Linear Momentum · easy · numerical
A 40 kg boy on frictionless ice throws a 2 kg ball at 10 m/s. His recoil speed is:
A. 0.5 m/s ✓ Correct
B. 0.05 m/s
C. 2 m/s
D. 5 m/s
Solution: 40v = 2×10 ⇒ v = 0.5 m/s backwards.
Q4 — Conservation of Linear Momentum · medium · numerical
A 10 g bullet is fired at 500 m/s from a 5 kg rifle. The rifle's recoil speed is:
A. 0.1 m/s
B. 1 m/s ✓ Correct
C. 10 m/s
D. 2 m/s
Solution: v = (0.01×500)/5 = 1 m/s. The rifle's KE is far smaller — momentum is shared equally, energy is not.
Q5 — Conservation of Linear Momentum · hard · numerical
A shell at rest explodes into two pieces with mass ratio 1 : 3. The ratio of their kinetic energies (light : heavy) is:
A. 9 : 1
B. 3 : 1 ✓ Correct
C. 1 : 1
D. 1 : 3
Solution: Equal/opposite momenta ⇒ KE = p²/2m ∝ 1/m ⇒ 3:1 — the lighter piece takes the lion's share of energy.
Q6 — Conservation of Linear Momentum · medium · numerical
A 60 kg man jumps with velocity 4 m/s from a stationary 240 kg trolley (free to roll). The trolley recoils at:
A. 0.5 m/s
B. 1 m/s ✓ Correct
C. 2 m/s
D. 4 m/s
Solution: 240v = 60×4 ⇒ v = 1 m/s opposite the jump.
Q7 — Conservation of Linear Momentum · easy · numerical
A 100 kg gun fires a 1 kg shell at 200 m/s. The gun's recoil speed is:
A. 2 m/s ✓ Correct
B. 20 m/s
C. 0.2 m/s
D. 4 m/s
Solution: v = 1×200/100 = 2 m/s.
Q8 — Conservation of Linear Momentum · medium · numerical
A 50 kg girl standing on a 150 kg stationary raft (calm water) walks at 2 m/s relative to the WATER. The raft moves at:
A. 1.5 m/s
B. 0.5 m/s
C. 2/3 m/s opposite to her ✓ Correct
D. 2 m/s
Solution: 50×2 = 150×v ⇒ v = 2/3 m/s backwards (total momentum stays zero).