Moment of Inertia of a drum with center axle

[aamir9]

I am confused with how to find moment of inertia of composite example. Like a hollow shell having one disc at each end and a shaft in the centre. How to find out Moment of Inertia if Force is applied tangentially on the shell and if force is applied tangentially on the shaft. Should I sum up three Inertias after calculating separately or I should consider it as one body and calculate it according as a solid mass?

 

[Sourabh N]

http://en.wikipedia.org/wiki/Parallel_axis_theorem"

 

[aamir9]

what about 2 discs fixed at the end of shell

 

[Sourabh N]

Find the moment of inertia of each component (here two discs and the hollow sphere) along their principal axes and then use parallel axis theorem.

Do you have an image of the setup you're talking about? From what I am imagining your setup is, it looks like the shaft goes through the center of both discs, perpendicular to the plane of disc and through one of the diameters of the shell. If this is correct, total moment of inertia would simply be the sum of moment of inertia of individual components.

 

[aamir9]

You understood correctly shaft is passing from the centre of the both discs perpendicularly and from the centre of the Hollow shell parallel to the axis of the shell and each disc is welded at the each end of the hollow shell.

Thanks
I understood what you mean just make it sure either summing up is solution or a one body calculation is proper way because it is a welded structure

 

[Sourabh N]

I understood what you mean just make it sure either summing up is solution or a one body calculation is proper way because it is a welded structure

Both approaches will work, except that one body calculation will be much more complex. You're welcome