1. The problem statement, all variables and given/known data A 399 kg piano slides 3.6 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. Calculate the force exerted by the man. 2. Relevant equations 3. The attempt at a solution Ok, I took mg(sin27)-(mu)mg(cos27)=0 339kg*9.8m/s^2*sin27-0.40*339kg*9.8m/s^2*cos27=0 and got 324N for an answer which is apparently not correct. I tried it several different ways and keep coming up with the same answer. Please help!