A 386 kg piano slides 3.7 m down a(n) 27° incline and is kept from accelerating by a man who is pushing back on it parallel to the incline. The effective coefficient of kinetic friction is 0.40 (assume the piano is sliding rather than rolling down). Determine the work done by the man.
a) 6000 J
b) 7500 J
c) 9000 J
d) 10500 J