AP Physics 1 Question 318: Answer and Explanation

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Question: 318

6. Question below refers to the graph above.

Two objects of masses m1 and m2 undergo a collision. The graph above shows their velocities with respect to time both before and after the collision. If m1 = 10 kg, then m2 must be

  • A. 5 kg
  • B. 10 kg
  • C. 15 kg
  • D. 20 kg

Correct Answer: C

Explanation:

C

For any collision, momentum must be conserved. That means m1v1,0 + m2v2,0 = m1v1,f + m2v2,f. Plugging in known values, that gives (10)(10) + m2(0) = (10)(-2) + m2(8). Solving for m2 gives m2 = 120/8 = 15 kg.