Power of a motor

Question:

Calculate the power needed to lift a load of 102.2 kg a distance of 68.58 cm in 3s.

Answer:

You actually already have the force – is it maybe the POWER of the motor that you would like?

Mass moved = 102.2 kg
Force needed to lift this at any speed = mass (102.2 kg) x gravity (9.8 m/s²) = 1002.3 N
Distance moved = 68.58 cm = 0.686 m
Time taken = 3 seconds.

The formulae that you use

Work done = force x distance = mass x gravity x height and
Power = work done/time taken

Your load is 101.2x9.8 = 1002.3 N

Work done = 1002.3x0.686 = 687.4 J

Power of motor needed = 687.4/3 = 229.1 W = 0.3 HP

(I have used 1 HP = 746 W)

(W - Watts, HP - horse power, J - Joules, N – Newtons)