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Two tuning forks are struck together and produce 4 beats each second. Then a small piece of tape is added to tuning fork 2, and when both forks are sounded again, the beat frequency becomes 6 per second. If tuning fork 1 has a frequency of 200 Hz, what was the initial frequency of tuning fork 2?

1. 202 Hz
2. 200 Hz
3. 204 Hz
4. 196 Hz

Correct answer: 196 Hz

Solution

The initial beat frequency of 4 Hz indicates that the frequency of tuning fork 2 is either 196 Hz or 204 Hz, since it is close to 200 Hz. After adding tape, the beat frequency increases to 6 Hz, which means the frequency of tuning fork 2 must have decreased, confirming that the initial frequency was 196 Hz.

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