NEED HELP.....conservation of energy...URGENT?

Question

a 2.0kg block situated on a rough incline is connected to a spring of negligible mass having a spring constant of 100N/m.the block is released from rest when the spring is unstretched, and the pulley is frictionless.the block moves 20cm down the incline before coming to rest. find the coefficient of kinetic friction between the block and the incline.
thx!!

to start with, i know the equation is
Ep = Ee + Eth(thermal energy)

Answer 1

Where is the pulley?
What is the angle of the incline?

Since I don't know where the pulley is, I will assume that the force of the spring is parallel to the incline.

The normal force is
cos(th)*m*g, where th is the angle of incidence between the incline and horizontal.
friction is µ*normal force.
And the energy lost is µ*cos(th)*m*g*x
where x is the distance traveled.
The potential energy lost from sliding down the incline is
m*g*sin(th)*x
and the energy stored in the spring at the end of the slide is
.5*k*x^2
sum all of these together and set equal to zero

m*g*sin(th)*x-
µ*cos(th)*m*g*x-
.5*k*x^2=0


µ=
(m*g*sin(th)-.5*k*x)/
(cos(th)*m*g)

Everything on the right is known except th

j