(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Suppose that the string in fig 8-12 (just a pendulum released from the side and falls to the bottom) is very elastic, made of rubber, say, and that the string is unextended at length l when the ball is released.

a) explain why you would expect the ball to reach a low point greater than a distance l below the point of suspension.

b) show, using dynamic and energy considerations, that if [tex]\Delta[/tex]l is small compared to l, the string will stretch by an amount [tex]\Delta[/tex]l = 3 mg/k, where k is the assumed force constant of the string.

2. Relevant equations

3. The attempt at a solution

for a, I suppose that the weight would displace the mass further down before the force of the string -kx "pulls" it back. but I'm not entirely sure..

for b) I tried to work out the change in K = Work from weight + work from string(spring like). I think if the change in l is small compared to l, then I can just say change in l + l = l, approximately. besides that, I'm not really sure.. any help please? thanks

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# Homework Help: Elastic pendulum energy problem

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