# Moment of inertia

1. Nov 29, 2008

### jimbo71

1. The problem statement, all variables and given/known data
see problem 8 attachment

2. Relevant equations
see problem 8 attempt attachment

3. The attempt at a solution
see problem 8 attempt attachment
I think I have solved the problem correctly and through my method I determine the moment of inertia to be 4.3 kg*m^2. However I'm not sure if the equations I used to find velocity and acceleration are valid in this situation.

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• ###### 2899-33757-problem 8 attempt.jpg
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2. Nov 30, 2008

### alphysicist

Hi jimbo71,

I think the assumption you have made (that is not necessarily true) is that the wheel is a uniform disk.

Once you found the linear acceleration of 0.75 m/s2, you can directly find the angular acceleration alpha from $a=r\alpha$.

Then you can use the torque equation like you did, but there is no need try to write out an expression for I, since I is what you want. Just use:

$$\tau = I\alpha$$

and solve for I.