(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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 2.0 m diameter and a mass of 270 kg. Its maximum angular velocity is 1500 rpm.

A) A motor spins up the flywheel with a constant torque of 58 N\cdot m. 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 2.2 s. What is the average power delivered to the machine?

D) How much torque does the flywheel exert on the machine?

2. Relevant equations

T = r x F

a = Tnet/I

I = [tex]\Sigma[/tex]mr^2

Krot = .5Iw^2

Period = 2pi/w

I=.5MR^2

3. The attempt at a solution

I first apologize for the lack of units, I'm not very solid with units while doing rotational work and get confused as to what they should be.

I = .5(270)(2)^2 = 540kg*m^2

1500rpm = 2pi/w = 25 rounds/seconds

w = 39.59

a = (58/540) = .107 (theta)/s^2

Actually, I just solved the first part when typing that out at 370s. The rest of the problems seem pretty linear, but I can't figure them out. I'm just plugging it into the Krot=.5Iw^2 forumla, and the answer comes out wrong.

I've tried this problem for a couple hours and asked tenish people from my physics class how to do it, but they couldn't figure it out either.

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# Torque Problems

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