To maintain a rotor at a uniform angular speed of 200rad s^ -1 , … - Vidyadip

Question

To maintain a rotor at a uniform angular speed of $200rad s^{-1}$, an engine needs to transmit a torque of $180Nm$. 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.

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Answer

Angular speed of the rotor, $\omega=200\text{rad/s}$ Torque required, $\tau=180\text{Nm}$ The power of the rotor (P) is related to torque and angular speed by the relation, $\text{P}=\tau\omega$ = 180 × 200 = 36 × 103 = 36kW Hence, the power required by the engine is 36kW.

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