- #1

SherBear

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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 m diameter and a mass of 270 kg. Its maximum angular velocity is 1500 rpm. How much torque does the flywheel exert on the machine?

## Homework Equations

to find Wf I used (1/2 K ) = 1/2 I wf ^ 2

then Wf=Wo+alpha(t)

then T for torque=I alpha

## The Attempt at a Solution

to find Wf I used (1/2 K ) = 1/2 I wf ^ 2

=(1/2 (9.4*10^5 (this is what the amount of energy stored) = 1/2 (70.3125) <--This number is I=1/2mr^2 (wf^2)

I rearranged this to find Wf

Wf^2= .5(9.4*10^5) / .5 (70.3125)

wf= sqrt 470,000 / 35.15

= sqrt 13371.26

wf = 115.63

then i used wf=wo+alphat to find the angular acceleration

alpha=wf / wo + t

alpha=115.63 / 157 rad/s+2.1 s

alpha = .7267

then torque=I alpha

=70.3125 (.7267)

T=51.09 N*M

It was wrong and I have no idea what I'm doing wrong