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dimpledur

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## Homework Statement

A wave takes 4s to travel form one end of the string to the other. Then the length is increased by 10%. Now how long does a wave take to travel the length of the spring?

## Homework Equations

v = sqrt ( FL/m)

F = -kx

## The Attempt at a Solution

If the original stretch was x, then an increase of ten percent would be:

1.1x.

So, if F = -kx, and since k is constant, if x increases by a factor of 1.1, then as does F. SO the tensional force is 1.1F the original.

v = sqrt ( 1.1F*L/m)

(delta d) / (delta t) = sqrt ( 1.1F*L/m)

taking the inverse:

(delta t) / (delta d) = sqrt ( m/1.1F*L)

where (delta d = 1.1L) since it has increased by ten percent.

So,

delta t = 1.1L*sqrt ( m/1.1F*L)

so the original delta t must increase by a factor of 1.1/sqrt(1.1)

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