AP Physics 1 Question 394: Answer and Explanation

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Question: 394

2. A 2 kg ball traveling at 25 m/s collides head on with a 1 kg ball traveling at 20 m/s. After impact, both objects reverse direction with the 2 kg ball traveling at 2.5 m/s and the 1 kg ball traveling at 35 m/s. What type of collision occurred?

  • A. Inelastic
  • B. Perfectly inelastic
  • C. Elastic
  • D. Cannot be determined

Correct Answer: A



The objects did not stick together after the collision, so (B) is wrong. To determine whether the collision is elastic or inelastic, calculate the total initial and final kinetic energies:

As kinetic energy was not conserved, the collision is inelastic.