(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A cloth tape is wound around the outside of a uniform solid cylnder (mass M, radius R) and fastened to the ceiling. The 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 intertia of a uniform solid cylinder about its center is .5MR^2.

a. Draw a FBD

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

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

2. Relevant equations

Well we just finished the chapter on angular momentum (and have thus completed basic angular motion), so I suppose all the angular stuff applies (torque, angular momentum, angular kinetic energy/potential energy, and the U(alpha)M equations)

I'm pretty sure this question should be solved using potential energy (mgh is converted into kinetic + angular kinetic energy, solve for a)

3. The attempt at a solution

a. The only relevant forces would be Tension going up (from the side of the cylinder) and Gravity going down (from the center of the cylinder), am I right?

b. This is the hard one. Am I right in saying that this is a conservation of energy question? All forces are conserved (no F applied, no friction) and so it should just be Gravitational Potential Energy converted to both angular kinetic and translational kinetic energy. And because you can convert angular acc. to translational acc., you should be able to solve for regular acceleration...? I don't think the problem should be that simple. (he asks for it in terms of g, no h involved I guess?)

c. Based on my answer to A, if there are no horizontal forces then the center of the cylinder should just go straight down (and not to the right or left). However, once it reaches the end of the tape it would probably (based on intuition) move toward the tape (or toward your hand)

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Dropping a cylinder

**Physics Forums | Science Articles, Homework Help, Discussion**