- #1

AlexPilk

- 26

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**Homework Statement**

Energy conversion efficiency of the elevator is 80%, it is working from 220 volts. How much current does the electro motor consume while it is constantly lifting the 500 kg cabin at 2 m/s.

**The attempt at a solution**

I=P/U, so I figured I need to know the power. P=F*v. I know the velocity (2 m/s) so I need the force.

F=m(g+a). Now this looks simple but for some reason I'm stuck. The acceleration = 0, so F must = mg?

If so - F=500*9.81=4905. (I suppose kilograms and m/s shouldn't be converted to anything).

P=9810W. If the efficiency is 80% - the whole power consumed is 9810/0.8=12262.5W.

And then I=12262.5/220=55.7 amps.

I'm not sure if it's too much or too little for an elevator, so I'm not really sure if I solved it correctly.

What do you think? Thanks!