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## Homework Statement

Flywheels are large, massive wheels used to store energy. They can be spun up slowly, then the wheel's energy can be released quickly to accomplish a task that demands high power. An industrial flywheel has a 1.5 diameter and a mass of 250kg. it's max angular velocity is 1200 rpm. a)a motor spins up the flywheel with a constant torque of 50Nm. How long does it take the flywheel to reach top speed? B) how much energy is stored in the flywheel? C) the flywheel is disconnected from the motor and connected to a machine to which it will deliver energy. half the energy stored in the flywheel is delivered in 2.0s. What is the average power delivered to the machine? D) How much torque does the flywheel exert on the machine?

3. The Attempt at a Solution

I've figured out the answers to A, B, and C. A) t=176.763 seconds. B) KE(r)=555168 J. C) Power= 138792 W. D) I read that P=torque*angular velocity; however, the answer in the book says 1.30 kNM and I continue to get 1104.47. Can calculator error really explain the difference or am I going wrong somewhere?