# Homework Help: How to maintain the same stationary wave pattern?

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1. Jul 7, 2015

### toforfiltum

1. The problem statement, all variables and given/known data

2. Relevant equations
not sure

3. The attempt at a solution
The answer is C, though I answered B. I don't understand why C is the answer.I thought that to maintain the same stationary wave pattern, I must maintain the speed of the stationary wave, and one way to do this is by reducing the wavelength of the wave. Instead, the answer suggests that we increase the speed of wave instead. Is it done to match the increase in frequency? But even so, why is B wrong?

2. Jul 7, 2015

### Orodruin

Staff Emeritus
In order to have a standing wave, the string length needs to be a half-integer multiple of the wavelength. You therefore cannot change the wavelength. How would you acheive this when the frequency changes? (Hint: How does frequency relate to wave speed?)

3. Jul 8, 2015

### toforfiltum

Ah, I forgot the fact that the wavelength of a stationary wave cannot be simply changed. Anyway, how do you increase the speed of wave on the string?

4. Jul 8, 2015

### Orodruin

Staff Emeritus
Have you seen the derivation of the wave equation for a string? If not you should look it up, it will tell you the wave velocity in terms of the density and string tension. Changing either will change the wave velocity.

5. Jul 8, 2015

Ok, thanks.