How Far Does a Block Compress a Spring on a Frictionless Surface?

[ice2morrow]

Homework Statement

A 4.0 kg block slides along a frictionless horizontal surface at 5.0 m/s. It runs into and compresses a spring with a spring constant of 200 N/m. How far does it compress the spring before it stops and changes direction?

Homework Equations

P.E. = 0.5 kx^2
K.E. = 0.5 mv^2

The Attempt at a Solution

x = sqrt (mv^2/k) = 0.707 m?

 

[Chewy0087]

that's right.