How Do You Calculate the Total Moment of Inertia for a Complex Wheel Assembly?

[physixnot4me]

Hi, I'm stuck on what I need to calculate the moment of inertia... in this type of question:

the wheel shown on a diagram has a central hub of radius 2m and a mass of 4kg, outside rim of radius 6m and a mass 1kg. each of the four spokes is 4m long and has a mass of 2 kg. find the moment of inertia about an axis through the centre perpedicular to the plane of the wheel. treat the hub as an empty sphere.

SO FAR, I've found the moment of inertial of the hub each spoke...
what is my next step?

Diagram is attached.

Thanks =)

 

[Astronuc]

The problem calls for finding the moment of inertia of a composite structure - hub, 4 spoks and rim. Also realize the spokes are rotating about an axis at one end.

Find some examples here -

http://hyperphysics.phy-astr.gsu.edu/hbase/mi.html#cmi

http://hyperphysics.phy-astr.gsu.edu/hbase/tdisc.html