Physics Force & Laws Of Motion Level: Misc Level

when two masses of unequal masses are hung vertically over a friction-less pulley of negligibly mass from a light string as shown in figure 3, the arrangement is called an Atwood machine.The device is sometimes used in the laboratory to measure the free fall acceleration. Determine the magnitude of the acceleration and the tension in the string for the masses M 1 =4.0 kg and M 2 =2.0 kg.