Calculation loss of energy due to friction?

[okgo]

Homework Statement

http://i43.tinypic.com/i1bq1i.jpg
I need help with number 9

Homework Equations

Wnet=change in KE
Wnc=Change in Energy

The Attempt at a Solution

I haven't been able to get the answer marked by the computer.
I tried Fs(h*cos15)=.5mv^2-mgh
and that is way off the anwser

 

[ideasrule]

I haven't been able to get the answer marked by the computer.
I tried Fs(h*cos15)=.5mv^2-mgh
and that is way off the anwser

Can you explain that equation? I don't understand what F and s are, or how you derived Fs(h*cos15).

 

[okgo]

sorry I meant that F(k) which is the force due to kinetic friction.
The equation for work is FDcos(theta). They gave use the height so I calculated the distance of the slope by Pythagorean theorem which gives cos(15)*the height.