Question

(8c7p44) The loaded cab of an elevator has a mass of 4000 kg and moves 207 m up the shaft in 31 s at constant speed. At what average rate does the force from the cable do work on the cab?

Answer 1

mass m = 4000 kg

elevator is moving with constant sped. so net force is T -m g = 0

T = m g = 4000 x 9.8 = 39200 N

   S = 207 m

time t = 31 sec

rate of work or power P = F X S / t = 39200 x 207 / 31 = 261754 .8 watts

                                                                                   = 2.6 x 10^5 watts