# Homework Help: What are the lowest two frequencies of the sound?

1. Jan 30, 2005

### Yoda13

I am having a problem finding where to start. The problem is this: A loudspeaker at the orgin emits sound waves on a day where the speed of sound is 340 m/s. A crest of the wave simultaneously passes listeners at the (x,y) coordinates (40m,0m) and (0m,30m). What are the lowest two frequencies of the sound? If the question asks for do different frequecies then there must be two different waves, right? I am having trouble thinking how to relate anything to finding the frequecy. Thanks for your help.

2. Jan 30, 2005

### christinono

Well, you know the speed, you have enough info to find the wavelength, and all you need to find is the frequency. To find the wavelength, place the 2 coordinates on a graph. (You know that waves travel in sinusoidal fashion, right?) Now, there are 2 possibilities for attaching the 2 points together. They could represent a quarter of a wavelenth, or half a wavelength. Now that I gave you a hint, you should be able to solve the problem.

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