Essential University Physics: Volume 1 (4th Edition) Clone

$a = \frac{ mg} {\frac{1}{2}M+m}$
We know the following equations: $ma = mg +( -T) = mg - \frac{1}{2}Ma$ $I = \frac{1}{2} MR^2$ $T = \frac{1}{2}Ma$ Solving the first equation for $a$ and combining these, we find: $a = \frac{ mg} {\frac{1}{2}M+m}$