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## Homework Statement

A 80.5 kg firefighter slides down a pole while a constant frictional force of 300 N retards her motion. A horizontal 20.0 kg platform is supported by a spring at the bottom of the pole to cushion the fall. The firefighter starts from rest 3.25 m above the platform, and the spring constant is 4000 N/m.

(a) Find the firefighter's speed just before she collides with the platform.

(b) Find the maximum distance the spring is compressed. (Assume the frictional force acts during the entire motion, and the spring is not compressed before the collision.)

## Homework Equations

U=mgh

K=1/2mv^2

Wspr=1/2kx^2

## The Attempt at a Solution

I easily found (a), the answer is 6.28 m/s. I cannot understand why (b) isn't right, though. I found the speed of the combined platform and firefighter after collision (5.03 m/s) through conservation of momentum. However, I try to plug this into another conservation of energy equation and it just doesn't work.