Question

A motor with 90% efficiency used in a crane of 50% efficiency, what is the

constant speed with which the crane lifts a body of mass 90 kg, if motor used is

of 4 H.P?​

Answer 1

Explanation:

Given, input power of motor = 5 kW = 5000 W

Efficiency of motor = 90 %

As we know that :

efficiency = output powerinput power ...........(1)

Therefore, output power of motor = 5000 X 90/100 = 4500 W

This output power of motor will act as input power for the crane.

Therefore, input power of crane = 4500 W

Given, efficiency of crane = 40%

Hence, output power of crane = 4500 X 40/100 = 1800 W (using eq. 1)

As we know that :

Power = Force X velocity

Therefore, 1800 = mg X velocity

1800 = 500 X 9.8 X velocity

On solving, we get :

velocity = 0.36 m/s

Answer 2

Answer:

0.36M/S gucudyxptxtozirzroxotxtoxtxotx