Physics
posted by Anonymous on .
A large store escalator that is designed to transfer customers to one floor to another, a vertical distance of 8.0m. It takes each person 20 seconds to ride from bottom to top of the escalator. Explain how you would determine the power of the escalator motor.

Guess mass of person, say 80 kg
guess how many on elevator, say 50 (guess high, we want a strong enough motor)
so total mass of people on elevator at one time = 80*50 = 4,000 kg
energy change = m g h
= 4,000 * 9.8 * 8 = 316,600 Joules
divide by 20 seconds
> 15,688 Watts
If the efficiency is 40% then you need about a 40 kw motor