Q.

An electric lift with a maximum load of 2000 kg (lift + passengers) is moving up with a constant speed of 1.5ms-1. The frictional force opposing the motion is 3000 N. The minimum power delivered by the motor to the lift in watts is (g=10ms-2)           [2022]

1 23000  
2 20000  
3 34500  
4 23500  

Ans.

(3)

Given that,

Mass of lift + passengers, m=2000kg

Speed, v=1.5m/s

Frictional force, f=3000N

Power delivered, P=Force×velocity                ...(i)

Force acting

F=mg+f

F=2000×10+3000

F=23000N

Using value of 'F' in equation (i),

P=23000×1.5=34500W