Imagine that you have a backpack full of books whose total mass is 24 kg. How much work does it take to raise it from the ground up to your shoulder?

Question

Imagine that you have a backpack full of books whose total mass is 24 kg.

a) How much work does it take to raise it from the ground up to your shoulder, an average distance of 1.7 meters for most people?

b) How much power does it take to raise the backpack in 1.7 seconds?

Answer 1

Work done = change in potential energy = mgh = 24 x 9.81 x 1.7 J

Power = energy change / time = 24 x 9.81 x 1.7 / 1.7 W = 24 x 9.81 W