Question

A loaded cab of an elevator has mass of 2500 kg and moves 250 m up the shaft in 50 sec at constant speed. At what average rate does the force from the cable do work on the cab?

• A. 1250 W
• B. 1000 W
• C. 100 W
• D. 125 kW

Answer 1

Answer:

D. 125 kW

Given data,

• mass of elevator = 2500 kg

• displacement = 250 m

• time = 50 sec

• g = 10 m/s²

Power = Work / time = W/t Work = force x displacement = F x d Force = mass x acceleration due to gravity = mg

• Work = mg x d

• Power = Work / time = (mgd)/t

= (2500 x 10 x 250) / 50

= (250 x 10 x 250) / 5

= 250 x 2 x 250

= 125000 W

= 125 kW