A block of mass m travelling at speed v strikes a stationary block of mass 4m. The lighter block comes to rest after collision. Determine coefficient of restitution.
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Question

A block of mass m travelling at speed v strikes a stationary block of mass 4m. The lighter block comes to rest after collision. Determine coefficient of restitution.

G1 Physics · Accepted Answer

Step 1 — Principle: For a one-dimensional elastic collision, conserve momentum and kinetic energy. Step 2 — Working: Momentum conservation gives mv=(4m)V, so V=v/4 for the heavy block. Step 3 — Working: Restitution e=(V-0)/(v-0)=1/4=0.25. Correct answer: B — 0.25.