Question

a block of mass 5kg and a block of mass 12kg are attached by a lightweight cord that passes over a frictionless

Answer 1

If the blocks are attached by a lightweight cord that passes over a frictionless pulley and both blocks are hanging, the acceleration can be found using Newton's second law:

$$m: T-mg=ma,\\ M: T-Mg=-Ma,\\ a=4.04\text{ m/s}^2,\\ T=69.2\text{ N}.$$