1. The problem statement, all variables and given/known data http://www.youtube.com/watch?v=cM3t6Td_rYs&feature=plcp 2. Relevant equations W=FΔrCosθ 3. The attempt at a solution My questions: 1) At around 2:30, when he draws out the free body diagram, I don't understand how he comes up with these Equations. For example, ƩFx = Fa - FgSinθ. Why is it "-"? Is it because the x component of gravity is acting against the Fa? 2) Same as above, but how does he come up with the sum of the forces on the Y component?