Why isn't disk moment of inertia included in T2?

[seto6]

Homework Statement

ok this is the problem :

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

 

[nickjer]

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.