Question

A 330- piano slides 3.8 down a 23 incline and is kept from accelerating by a man who is pushing back on it parallel to the incline.
a.Determine the work done by the force of gravity.
b.Determine the work done by the man on the piano.

Answer 1

you need to add units to the measurements. Ill assume the following: 330 kilograms, 3.8 meters, 23 degrees.

mass*gravity*amount of gravity working=
330*9.8*cos(90-23)=force or work of gravity

if the man fights gravity the entire time then his force is equal and opposite to gravity.