# Waves (Sound and light)

1. Aug 26, 2014

### Codav

1. A string that is 6.0m long is vibrating with three loops in it. The frequency of the source is 16.5Hz.

What is the fundamental frequency of the string?

What is the speed of the waves in the string?

Explain whether or not a source of frequency of 28.5Hz causes a standing wave in the string.

3. Info: 6m long string. Source frequency is 16.5Hz. There are 3 loops.
Find wavelength:
6m/3=2m
Each loop is 2m.
1 loop is half a wavelength.
λ=2*2
λ=4m
Since the frequency is 16.5Hz with three loops, to find fundamental frequency you just divide by three.
16.5/3=5.5Hz
The fundamental frequency is 5.5Hz
Find speed with velocity equation: v=ƒ*λ
v=16.5*4
v=66m/s
The speed of the waves in the string is 66m/s

A source frequency of 28.5Hz would not cause a standing wave in the string because it is not a multiple of the fundamental frequency 5.5Hz.
28.5Hz/5.5Hz=5.182Hz

2. Aug 27, 2014

### BvU

What's your question? Or do you just want an approval stamp from PF ?
(By the way: I can't find anything wrong with what you write...
except: Hz/Hz is not Hz. The quotiënt is a simple number
)