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

Two identical cars approach each other on a straight road. The red car has a velocity of 40MPH to the left and the green car has a velocity of 80MPH to the right.

A spring is attached to the front bumper so that a head-on collision will be elastic. If the maximum indentation of each bumper is 5cm, what is the spring constant of the bumpers?

2. Relevant equations

KE= 1/2 m v^{2}

EPE = 1/2 k x^{2}

3. The attempt at a solution

The kinetic energy must be absorbed by the two springs, so KE_{red car}+ KE_{green car}= 2 * EPE, correct? Doing this I get a value of 320410m, but this doesn't seem right. Shouldn't I be able to get an answer that is not in terms of the mass? Did I set up the equation wrong and somehow the masses should cancel?

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# Homework Help: Finding spring constant in elastic collision of equal masses

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