1. Mar 14, 2007

### fruitl00p

1. The problem statement, all variables and given/known data
This problem consists of 3 parts. Though my trouble in only part 3, I figured that by providing all of the part might show someone clues that I might have missed....

1. If instead of the force F an actual mass m=.0630 kg is hung from the string, find the angular acceleration of the cylinder. (I answered this correctly)

2. How far does m travel downward between .590s and .790s after the motion begins (answered this one as well)

3. The cylinder is changed to one with the same mass and radius, but a different moment of inertia. Starting from rest, the mass now moves a distance .0362 m in a time .510s. Find Icm of the new cylinder.

2. Relevant equations

a.) K=1/2*M*Vcm^2 + 1/2*Icm*w^2
b.) K1 + U1 =K2 +U2
c.) Vcm= Rw

3. The attempt at a solution

First I used equation a. to try to get Icm by itself.
2(Mgh -1/2MVcm^2)/w^2 =Icm
Then I used equation b to get w by itself, changing the above equation to:
2(Mgh -1/2 MVcm^2)/ (Vcm/R)^2 = Icm

At this point I realized that I don't know what the new mass and radius is, just that it is the same value. Also, I do not know what Vcm is. Plus, the fact that the problem provides the time it takes for the object to descend makes me think that I am missing a step since I have yet to apply it.

This particular homework problem is due tomorrow so I hope that I have provided enough information that someone can explain whether or not I am on the right track, etc.