A wavy problem what will happen?

1. Apr 20, 2015

mooncrater

1. The problem statement, all variables and given/known data
When I was reading waves from my book I noticed that the part of string in wave motion should be longer than the part of string not in wave motion . But throughout we have the same string, so to consider this change either the source will come ahead or the string will expand(increase its length) a little bit. So which of the two will happen?

2. Relevant equations
none

3. The attempt at a solution
-

2. Apr 20, 2015

AlephNumbers

Hmmm. I never really thought about that.
I think that most real strings would stretch if they were fixed at both ends. For example, if you pluck a guitar string, the string will pull on the guitar at each end where it is attached to the guitar. The string stretches a little, and the guitar bends a little.
If the string was fixed at one end and not at the other, and you send a pulse from the fixed end towards the loose end, then I think that the loose end would be pulled towards you a little bit.

This is under the assumption that you are talking about transverse waves.

3. Apr 20, 2015

mooncrater

So what I made out of your reply is that the answer to my question is conditional . When both ends are bound then the only option remains for the string is that it will stretch. But for the case when one end is free , I have a problem . We know that the person has to pull the string for continuous wave motion. So shouldn't here too the string elongate?