AP Physics 1 Question 264: Answer and Explanation

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Question: 264

10. Two cars starting from the same position begin driving along the same horizontal axis. If Car A's horn emits a sound wave, which of the following pairs of velocities would result in the greatest difference between the wave's source frequency and the perceived frequency for Car B?

Car A    Car B

  • A. 20 m/s to the right    30 m/s to the right
  • B. 10 m/s to the right    25 m/s to the right
  • C. 10 m/s to the left    10 m/s to the right
  • D. 30 m/s to the left    30 m/s to the left

Correct Answer: C

Explanation:

C

The degree to which the Doppler effect alters a wave's frequency is based on the relative motion between the wave's source and detector. In this case, the relative motion between the objects in the answer choices is 10 m/s, 15 m/s, 20 m/s, and 0 m/s. Therefore, the scenario in (C) will have the greatest difference between the source and detector.