SAT Subject Physics Practice Question 287: Answer and Explanation

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Question: 287

58. A pair of tuning forks produce sound waves that travel through the air. The frequency of the sound waves produced by the first tuning fork is 440 Hz, and the frequency of the sound waves produced by the second tuning fork is 880 Hz. If v1 denotes the speed of the sound waves produced by the first tuning fork and v2 denotes the speed of the sound waves produced by the second turning fork, then

A. v1 = 2v2
B. v1 = 4v2
C. v1 = v2
D. v2 = 2v1
E. v2 = 4v1

Correct Answer: C

Explanation:

The speed of a wave is determined by the properties of the medium, not by the frequency. (An exception to this general rule includes light through a transparent material medium such as glass—the speed depends slightly on the frequency, and this accounts for the phenomenon of dispersion, which can be seen in the familiar spreading of white light into its component colors when it passes through a prism.) Since wave speed is independent of frequency in the situation described here, the answer is C.

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