Applying energy and work equations to homework problems

[takeiteasy]

Homework Statement

All of them in the picture attached.

Homework Equations

Energy and work equations;the change of the energy is equal to work done.

The Attempt at a Solution

ACtually,I don't know how to appy these equations if you can draw the forces and relationships and how to apply them into equations the logic behind it,I would be appreciated.Thanks.

 

[juana_sm]

I think it's not the best idea to solve this task using energy and work. Maybe it would be easier to use the 1-st Newton's law (for solving the b) task):
the friction forse is: mu*(Mg-k*x*sin(theta)), and it is equal to k*x*cos(theta)