Q. A ball moving with velocity 2 m/s collides head on with another stationary ball of double the mass. If the coefficient of restitution is 0.5 then their velocities (in m/s) after collision will be
A) 0, 2
B) 0, 1
C) 1, 1
D) 1, 0.5
Explanation
[Solution from source] Momentum: m×2 = m v₁ + 2m v₂, so v₁ + 2v₂ = 2. Restitution: v₂ − v₁ = 0.5 × 2 = 1. Solving gives v₂ = 1 m/s and v₁ = 0, i.e. velocities 0 and 1 m/s. The pair 1 and 1 would need perfectly inelastic sticking, which conserves momentum only if v = 2/3. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.