# Homework Help: Rotational Intertia of a rotating Space Station

1. Jun 21, 2013

### slingshotnz

1. The problem statement, all variables and given/known data
Four rockets attached to a (wheel) space station exert a force of 65.5N to rotate it . The space station's angular velocity is increased at a constant acceleration of 3.63 x 10-3 rads-2. Each rocket is 11.2m away from the centre. Calculate the rotational inertia of the system.

2. Relevant equations

τ=Iα , others unknown.

3. The attempt at a solution
Torque of all 4 rockets. (65.5N * 11.2) * 4 = 2934.4N
since τ=Iα, I=τ/α hence I= 2934.4/3.63x10-3 = 808374.7Kgm2

Can anyone confirm if this is the correct method.

Thanks.

Last edited: Jun 22, 2013
2. Jun 21, 2013

### SteamKing

Staff Emeritus
The units for inertia are wrong. What are the derived units for the Newton? (Hint: F = ma)

3. Jun 22, 2013

### slingshotnz

Sorry Kg metres squared?. Other than that does the working look fine? I appreciate the advice.

Last edited: Jun 22, 2013
4. Jun 22, 2013

### haruspex

Not sure, but I think SteamKing may be referring to this item:
force in N * distance in m gives what units?