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Would appreciate any help anyone has for me.

I am building a physical pendulum of sort, which consists of a hollow cylinder, which I am going to fill with sand. I am going to let the sand flow out of the pendulum and investigate the change in period with changing mass.

I also am mathematically/computationally modelling this. I am currently trying to figure out the equations of motion that I'm going to need to model this. I know the equation for the period of a physical pendulum is T=2*pi*sqrt(I/mgh), where h will be changing at a constant rate.

I'm wondering how to calculate the moment of inertia. I've found equations on hyperphysics for common moments of inertia (http://hyperphysics.phy-astr.gsu.edu/HBASE/mi.html#) but as my pendulum is going to be partly a solid cylinder and partly a hollow one, I'm not sure how to merge these equations. Has anyone got any advice?

Thanks in advance :)

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# Model of Physical Pendulum

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