Dynamics Question: Mass Moment of Inertia & Work Done by Gravity

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Homework Statement



ok this is the problem :

5os8t4.jpg


i kinda get how to do it (using energy + work method)

i don't get it why they don't include the mass moment of inertia of the disk for T2
and why did they only calculate the work done by gravity only for one point which is of ab.


2. solution

30kx6qf.jpg
 
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Who gave you that solution? I didn't look that far into it, but I am confused with their units. All of a sudden ft changed to meters. And I am not sure but it looks like they divided pounds by m/s^2 and got kg. I would not trust that result at all.
 

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