A 150kg safe on a frictionless casters is to be raised 1.20 m off the ground to the bed of a truck. Planks 3.0 m long are available for the safe to be rolled along. How much force is needed to push the safe up to the truck

Answer 1

Force x (plank length), which is the work done, must equal the increase in potential energy: (mass) x g * (height raised)
F * 3.0 = 150 x 9.81 x 1.20

Solve for F, which will be in Newtons

Answer 2

588