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Fork P has a frequency of 426 Hz. Fork Q is unknown…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Fork P has a frequency of . Fork Q is unknown. Sounded together, they give 6 beats each second. A small piece of wax is stuck on a prong of Q, and now they give 4 beats each second. (a) Find the frequency of Q without the wax. (b) Find the frequency of Q with the wax.
Need a reminder? The key ideaShow
Two sounds of frequencies and that are close give beats:
You hear the pitch . Wax lowers a fork's frequency, filing raises it, tightening raises a string's.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, compare your working with the solution.
(a) Q is or . The wax lowers Q's frequency.
- If Q were , the wax would take it further below P. The beats would get faster.
- If Q is , the wax brings it closer to P. The beats get slower, as seen.
So Q is .
(b) With the wax, Q is still above P and gives 4 beats: .
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