a 295 kg piano slides 4.0 m down a 30 degree incline and is kept from accelerating by a man who is pushing back on it parallel to the incline and the...

a 295 kg piano slides 4.0 m down a 30 degree incline and is kept from accelerating by a man who is pushing back on it parallel to the incline and the effective coefficient of kinetic friction is .4. calculate the force exerted by the man