Assumptions - Applet Atwood

The applet Atwood simulates the motion of two masses connected by a massless, ideal string which passes over a massive pulley.

The Applet makes a number of assumptions:

1. the string connecting the masses is massless and does not stretch
2. the string does not slip on the pulley
3. there are no external, dissipative forces (air resistance, friction in the pulley, etc) present.