# Moment of Inertia of a pulley

## 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.

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.

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rock.freak667
Homework Helper
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?

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

rock.freak667
Homework Helper
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.

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

rock.freak667
Homework Helper
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?