Coefficient of kinetic friction of skis

[Kster]

Homework Statement

Sam, whose mass is 75 kg , takes off down a 50 m high, 10 degree slope on his jet-powered skis. The skis have a thrust of 200N . Sam's speed at the bottom is 40 m/s . What is the coefficient of kinetic friction of his skis on snow?

Homework Equations

Fk = uk N
u = Fk / N

The Attempt at a Solution

there's an answer to this question in the back of my book and I've been trying to figure out why the author got this answer uk = 0.165 . The reason I am doing this is to apply the same technique to figure another problem like this on masteringphysics.com. Thank you for your help!

 

[saket]

Use work-energy principle.