A 4 kg trolley moving at 6 m/s collides with a stationary 2 kg trolley and the two stick together. What is their common speed?
Answer and explanation
Correct answer: A. 4 m/s
- Step 1: Momentum is conserved: , so m/s. Answer: 4 m/s. Why not the others: 6 m/s: ignores the second mass. 12 m/s: divides by the target mass only. 2 m/s: gives the speed lost.
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