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**[SOLVED] Conservation of Energy Problem - Need Help**

**1. Homework Statement**

A 2.0 kg cart has a sping with k= 5000 N/m attached to its front, parallel to the ground. This cart rolls at 4.0 m/s toward a stationary 1.0 kg cart.

a) What is the maximum compression of the spring during the collision?

b) What is the speed of each cart after the collision?

**2. Homework Equations**

KE=(1/2)mv^2 Us=(1/2)kx^2

**3. Attempt at a solution**

I got the first part:

Using first conservation of momentum and assuming the cars stick together momentarily

then using conservation of energy

(2kg)(4m/s)=(3kg)v1

v1= 2.67 m/s

(.5)(2kg)(4m/s)^2=(.5)(5000N/m)(x)^2 + (.5)(3kg)(2.67m/s)^2

x= .046 m

But I'm not sure what to do with the second part. Any suggestions?