# Standing waves on a moving string

1. Jul 13, 2015

### d7vid

Hello,
I have the configuration as shown in attached picture. I know how to calculate string tension and measure frequency if the string is not moving. But what happens if the string is moving at a constant speed? Are there still standing waves? Can we still calculate the string tension? What if the speed of a string is slow in comparison to frequency of standing waves?

Thanks!

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2. Jul 13, 2015

### Dr. Courtney

First, this may belong in a HW section and need to follow the HW guidance requirements.

Second, consider why and how would the equations change if a string is moving?

3. Jul 13, 2015

### Shreyas Samudra

dr. courtney , tell me how an oscillator would produce a wave on the string ??

4. Jul 13, 2015

### Dr. Courtney

Strings tend to start vibrating if any one of their resonance frequencies are excited. If an oscillator excites a resonant frequency, a string will vibrate, producing a wave.

5. Jul 13, 2015

### Shreyas Samudra

actually i meant to say how an oscillator would produce a wave on the string , when the string is moving with some speed ??
don't you think that - the attempt of oscillator for producing a wave may lead to some unordered stuff happening on the string , as it is moving ?? !

6. Jul 14, 2015

### d7vid

Sorry if it is in the wrong section.
I was thinking that waves moving in one direction are "sped up" because of the moving string and waves travelling in the opposite direction are "slowed down". Would we actually see 2 different frequencies or am I completely wrong?

7. Jul 14, 2015

### nasu

The speed of the wave in respect to the medium (string) is not changed by the motion of the string.

8. Jul 15, 2015

### d7vid

I understand that. I was talking from the point of view of an outside observer.

9. Jul 15, 2015

### nasu

That point of view is irrelevant for the frequency of the standing waves.

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