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## Homework Statement

A wheel free to rotate about its axis that is not frictionless is initially at rest. A constant external torque of +43 N·m is applied to the wheel for 20 s, giving the wheel an angular velocity of +610 rev/min. The external torque is then removed, and the wheel comes to rest 120 s later. (Include the sign in your answers.)

(a) Find the moment of inertia of the wheel.

(b) Find the frictional torque, which is assumed to be constant.

## Homework Equations

Rotational Momentum

(0.5)(moment of inertia)(omega^2) = Torque * change in time

## The Attempt at a Solution

A) The angular velocity is given in revolutions, so I multiply it by 2 pi in order to get it in radians/sec. I plug that result into the omega of the equation, plugged 43 into torque, and 20 into the time. I know there's more I need to do from there since solving for inertia at this point gave me a result less than 1 which is incorrect, but I'm not sure what that next step is.

B) I think I need to solve for A before I can solve for this.

Thanks. I'm also new to these forums.