Calculating Moment of Inertia for a Pulley with Attached Mass

[Keithkent09]

Homework Statement

A 1.65 kg mass is attached to a light cord that is wrapped around a pulley of radius 4.65 cm, which turns with negligible friction. The mass falls at a constant acceleration of 2.40 m/s2. Find the moment of inertia of the pulley.

Homework Equations

I=mr^2
Torque=I*alpha

The Attempt at a Solution

I tried to just square the radius given and multiply it by the mass but that did not work. I also tried to find the Torque using T=mgr. And then divided that number by the acceleration/radius in order to get the angular acceleration.

 

[rock.freak667]

I also tried to find the Torque using T=mgr. And then divided that number by the acceleration/radius in order to get the angular acceleration.

So what did that give you?

 

[Keithkent09]

It gave me the wrong answer. I guess that is not the correct way to find the torque

 

[rock.freak667]

It gave me the wrong answer. I guess that is not the correct way to find the torque

That should be the correct way to do it, post your work.

 

[Keithkent09]

I figured it out using a different set of equations. Thanks for your help though, sorry to waste your time.

 

[rock.freak667]

I figured it out using a different set of equations. Thanks for your help though, sorry to waste your time.

What equations did you use by chance?