AP Physics 1 Question 40: Answer and Explanation

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Question: 40

10. A small cart of mass m is initially at rest. It collides elastically with a large cart of mass 4m and velocity v. The large cart loses half its kinetic energy to the little cart. The little cart now has a velocity of

  • A. 1.41v
  • B. v
  • C. 2v
  • D. 4v

Correct Answer: A


A The small cart starts with no kinetic energy because it is at rest. The large cart starts with K = (4M)v2 = K = 2Mv2. If it gives half the kinetic energy to the small cart as it transfers K = Mv2. The equation for the kinetic energy of the small cart is now