Answer: Given mass of man = 85kg
Distance crate was pushed = 4m
Force exerted on crate = 500N
Angle inclined = 20°
Let Total force exerted Ft = (mg * sin(20)) + 500
Ft =( 85*9.81* sin20°) + 500
Ft = 758N
Work done Wd = Ft * distance
Wd = 785 * 4 = 3.14 * 10^3J