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February 28, 2015

February 28, 2015

Posted by **Anonymous** on Sunday, June 29, 2014 at 1:06am.

- Physics -
**Damon**, Sunday, June 29, 2014 at 6:23amGuess 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

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