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

Here's the problem in a JPG, with the image:

http://docs.google.com/Doc?id=d277r7r_50c9trfbdr [Broken]

(the 25 points is b/c it's a practice test)

2. Relevant equations

3. The attempt at a solution

A)KE=0, PE=0 (defined to be at cylinder's initial position)

B)PE=Mg(-h)

C)Final KE=.5*M*(2gh)^2 (To get this, I used the v^2=vi^2 + 2aX equation, plugged it in for v^2 in KE=.5mv^2)

However, I don't think my equations are right because if my KE was that, there would have to be extra energy put into the system for the yo-yo to rotate at all, thus there would be no rotational kinetic energy, which doesn't seem to jive with the original provlem. Where am I going wrong?

**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: Rotational Kinematics-YoYo Dropping from Ceiling

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