Question

To maintain a rotor at a uniform angular speed of 200 rad/s, an engine needs to transmit a torque of 180 N m. 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

Given, the uniform angular speed of the rotor is 200  rad/s and the transmitted torque is 180 N-m.

Let T be the transmitted torque and ω be the angular speed of the rotor.

The power (P) required by the engine is given by,

$P=T\omega$

Substitute the values in the above equation.

$P=(180N-m)\left(200rad/s\right)=36000W=\left(36000W\right)\left(\frac{1kW}{1000W}\right)=36kW$

Thus, the power required by the engine is 36 kW.