Why is it that the equation for work done to stretch a spring is(adsbygoogle = window.adsbygoogle || []).push({});

W = 1/2k(x_{2}^{2}-x_{1}^{2})

while the work done by a spring on an object is

W = 1/2k(x_{1}^{2}-x_{2}^{2}) ?

That is, how come it's x_{2}^{2}-x_{1}^{2}for the first case, and x_{1}^{2}-x_{2}^{2}for the second?

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# Work done to stretch a spring vs Work done by a spring?

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