# Torque and angular acceleration problem

1. Apr 24, 2013

### freshcoast

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

2. Relevant equations

Ʃ$\tau$ = I$\alpha$
ƩF = ma

3. The attempt at a solution

I was able to calculate A and B which I am confident is correct..

for part C is what I'm having trouble with. Since both disks are fixed together, does that mean they share the same angular acceleration? if so I think the way to go about this is I apply the equation

Ʃ$\tau$ = I$\alpha$

where it will be T1R1 - T2R2 = I$\alpha$ and I just solve for alpha.

but since they are now accelerating.. doesn't that change each tension to be t = mg + ma? instead of just t = mg ? which then makes it much more difficult to solve..

unless if the tensions are just mg then it will be fairly easy to solve since I can find the alpha of the rotating system then just apply the equation

a = $\alpha$R

and calculate the a for each, and from there I will be able to find the tensions in each rope.

2. Apr 24, 2013

### Simon Bridge

Yes - that is what "fixed together" means. You needed to assume this to do (a) and (b).

Use the free-body diagram to inform you of the tensions. Don't anticipate.