Consider the following system in equilibrium. The disk has radius $R$ and the rod has length $2R$. The rod is attached to the disk and the block is attached in place to the rod (it does not move radially).
The forces present are the tension T on the string and the 3 gravity forces (on the block, rod and disk).
The condition that the net torque vanishes results in
First question: What is the result of requiring all forces to vanish? It seems that there are 3 vertical gravity forces and one horizontal force only (tension T) so how can those forces cancel each other?
Second question: How is the linear velocity of the block related to the angular acceleration of the disk once we cut the string?