A 50 kg box is lifted by a person pulling a rope a distance of 20 meters straight up at a constant speed.

Question

How much Power is required from the person in order to complete this task in 8 seconds?

Answer 1

Power is defined as the rate of doing work or Power = Work / time. The work in this case is mass x gravitation constant x distance, P = 50 kg x 9.8 ms^-2 x 20 m = 9800 joules. Power is then 9800 j / 8 s = 1225 watts (a Watt is 1 joule per second).