Question

A man is loading a truck with crates that weigh 120 N each. He lifts each crate vertically
through a height of 2 m.
Calculate the work done and the amount of energy spent by the man while lifting one
crate.

Answer 1

Answer:

240 J, 240 J

Explanation:

First, let us see how much energy is required to raise 1 crate 2 m in the air. Work done can be calculated as force x displacement.

1.) Energy Spent by man:

Energy spent by the man is the energy gained by the crate, as no external force is acting.

To raise the crate by 2 m, energy spent would be:

mgh = (Weight)h = 120 x 2 = 240 J

2.) Work done by man:

Work done is force applied by the man multiplied by the distance parallel to the force applied. So, here, force applied is mg which is 120 N. Displacement is +2 m, so work done:

W = 120 x 2 = 240 J

You can observe that energy spent by the man is the work done by the man. This is because work done is nothing but energy only, and is calculated along with energy.

Hope it helps!