Question

To maintain a rotor at a uniform angular speed of 200 rad s–1, an engine needs to transmit a torque of 180 Nm. What is the power required by the engine? (Note: uniform angular velocity in the absence of friction implies zero torque. In practice, applied torque is needed to counter frictional torque). Assume that the engine is 100 % efficient

Answer 1

Uniform angular acceleration in the absence of frictional force implies zero torque . in practice , applied torque is needed to counter frictional torque .

Assume that efficiency of engine is 100% .
Given,
w = 200 rad/sec
torque = 180 N.m
Power required by engine = torque × angular speed
= 180× 200
= 36000 watt
= 36kw

Answer 2

Answer:

Given: The angular speed of the rotor is 200 rad/s.

The torque needed to be transmitted by the engine is 180 Nm.

The power of the rotor required to transmit energy to apply a torque τ to rotate a motor with angular speed ω,  

P=τω

=180×200W

=36kW