A trolley moving at collides with a stationary trolley and they stick together. What is their common speed after impact?

Answer and explanation

Correct answer: A.

  1. Step 1: Momentum is conserved: .
  2. Step 2: , so m/s.
Answer
.
Why not the others: : keeps the original speed. : assumes the speed is shared equally. : gives the momentum, not the speed.

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