# Homework Help: Rotation, torque, angular momentum?

1. Apr 1, 2012

### kjn11994

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

A cloth tape is wound around the outside of a uniform solid cylinder (mass M, radius R) and fastened to the ceiling as shown in the diagram below. They cylinder is held with the tape vertical and then released from rest. as the cylinder descends, it unwinds from the tape without slipping. The moment of inertia of a uniform solid cylinder about its center is 1/2MR^2.

diagram: http://imgur.com/h0v07

A. draw and label a diagram of the cylinder showing all the forces acting on the cylinder after it is released. label each force clearly.

B. in terms of g, find the downward acceleration of the center of the cylinder as it unrolls from the tape

C. what is the angular velocity of the cylinder after it has descended 3 meters?

D. while descending, does the center of the cylinder move toward the left, toward the right, or straight down? Explain.

2. Relevant equations

KEr=1/2MR^2

3. The attempt at a solution

i have no clue how to solve this

2. Apr 1, 2012

### vela

Staff Emeritus
You need to show us you made some effort before you can get help here. Did you at least do part A?

3. Apr 1, 2012

### kjn11994

i honestly have no idea where to start...

4. Apr 1, 2012

### vela

Staff Emeritus
Then I would suggest you go back and read your text, particularly the examples. Identifying the forces is pretty basic. You should have covered it in class weeks ago. You can open a new thread after you've made some sort of attempt at solving the problem on your own.