AP Physics 1 Question 221: Answer and Explanation

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Question: 221

2. A ball of mass 0.5 kg, initially at rest, acquires a speed of 4 m/s immediately after being kicked by a force of strength 20 N. For how long did this force act on the ball?

  • A. 0.01 s
  • B. 0.1 s
  • C. 0.2 s
  • D. 1 s

Correct Answer: B

Explanation:

B

The impulse delivered to the ball, J = FΔt, equals its change in momentum. Since the ball started from rest, you get