Posted by Jon on .
The two masses (m1 = 5.0 kg and m2 = 3.0 kg) in the Atwood's machine shown in Figure 1023 are released from rest, with m1 at a height of 0.91 m above the floor. When m1 hits the ground its speed is 1.5 m/s. Assume that the pulley is a uniform disk with a radius of 12 cm.
Determine the mass of the pulley.

Physics 
drwls,
Use a conservation of energy approach, and include the rotational kinetic energy of the pulley, KEr
KEr = (1/2)I w^2 = (1/4) m V^2
The radius of the pulley will cancel out. m is the mass of the pulley.
potential enegy change
= (1/2)[m1 + m2 + (m/2)] *V^2
I would need to see your figure 1023 to know how the potential energy is related to the height.