Question

A frictionless massless pulley has 7 kg tied to a cable on the left side and an unknown mass (M) on the right. The unknown mass accelerates downward at 6.6 m/s2

What is the accelerationof the system/tension of the rope

Answer 1

tension at the left side:
T=7*6.6+7*g
that has to be the tension on the right side also...
T=M*g-M*6.6
so M= 7(6.6+g)/(g-6.6)