Rotational dynamics - System in Equilibrium

1. Apr 20, 2012

numan-chris

Hi all, first year MechEng student here, final question of the final assignment of the year, would appreciate any assistance:

1. The problem statement, all variables and given/known data
A 0.150 kg yo-yo has an outer radius R that is 5.60 times greater than the radius r of its axle. The yo-yo is in equilibrium if a mass m is suspended from its outer edge, as shown in the figure .

(http://session.masteringphysics.com/problemAsset/1123236/2/Walker.11.95.jpg)

Find the tension T1

Find the tension T2

Find the mass 'm'

2. Relevant equations
w=mg
I=1/2mr2

3. The attempt at a solution
Having drawn FBD's for the system, I found no problem in deriving an equation for T1 (if I find this I'm sure I will have no problem with the rest) however it contained variables which when submitted, I was told the answer was not to contain. After much struggling I can't see how it can be done.

2. Apr 21, 2012

tiny-tim

welcome to pf!

hi numan-chris! welcome to pf!

show us your full calculations, and then we'll see what went wrong, and we'll know how to help!

3. Apr 21, 2012

numan-chris

thank you for the reply, managed to solve the problem myself about 5 minutes ago, was missing a variable from one of the simultaneous equations I needed, novice mistake!