An Atwood's machine (see the figure below) consists of two masses: one of mass 1.23 kg and the other of mass 4.96 kg. When released from rest, what is the acceleration of the system? (Enter the magnitude in m/s2.)

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.

its c its is a mixture of gases