A man whose mass is 70 kg walks up to the third floor of a building. This is a vertical height of 12 m above the street level.

Question

A man whose mass is 70 kg walks up to the third floor of a building. This is a vertical height of 12 m above the street level.
(a) How many joules of work has he done?
(b) By how much has he increased his potential energy?
(c) If he climbs the stairs in 20 sec, what was his rate of work, ie. power?

Henry · Accepted Answer

Fm = mg = 70ikg * 9.8N/kg = 686N. = Force of the man. a. W = Fm*d = 686 * 12 = 8232J. b. PE = mg*h = 686 * 12 = 8232J. c. P = F * d/t = 686 * 12/20 = 411.6J/s = 411.6 Watts.