A block of mass m slides down a flat surface inclined at angle θ above horizontal. The coefficient of kinetic friction between the block and surface is μ . The block slides a distance D down the surface at a constant speed v, from x=0 to x=D for x-axis pointing down the incline.
a) Graph the work done by friction versus time from t=0 to t=D/v. Is it positive or negative?
b) What is the power delivered to the block by gravity as it slides down the incline?