Atwood Machine
Draw a FBD for M1 and M2 in your Atwood machine. Draw force arrows for the force due to gravity acting on both masses and the force of tension
Use Newton's Second Law to write an equation for each mass of the Atwood machine. Solve these two equations for the acceleration of the system.
Using the masses M1 and M2, use the above expression to calculate the acceleration of the system. How does this value compare to your experimentally measured acceleration? What factors may cause discrepancies between the two values?