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

Answer

Angular speed of the rotor, ω = 200 rad/s

Torque required, τ = 180 Nm

The power of the rotor (P) is related to torque and angular speed by the relation:

P = τω

= 180 × 200 = 36 × 103

= 36 kW

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

Answer 2

Explanation:

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

hope you get it now....