A cart of mass m = 2 kg carrying a spring of spring constant k = 48 N/m and moving at speed v = 3.2 m/s hits a stationary cart of mass M = 10 kg. Assume all motion is along a line.(adsbygoogle = window.adsbygoogle || []).push({});

a) What is the speed of the center of mass of this system?A: .5333 m/s

b) When the spring is at its maximum compression, with what speed are the carts moving in the lab frame?A: .5333 m/s

c) How far will the spring be compressed?

This is where I have trouble. I know potential energy of spring = 1/2kx^2, but how do i find initial kinetic energy?

The equation i tried was the following:

(1/2)*m*(Vi+Vcm) = (1/2)*k*x^2

i also tried (1/2)*m*(Vi) = (1/2)*k*x^2, but neither of these worked.

any suggestions?

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# Homework Help: Momentum with spring collision

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