This video describes how to find a symbolic expression for the acceleration of the three-object system and the tension in one of the strings during acceleration. This three-object system is a more complicated version of a “modified Atwood's machine" that consists of a block or cart on a horizontal surface, connected with a string to a hanging mass over a pulley. The pulleys in this video are considered "ideal" (negligible mass and friction), so the tension in the string is the same on either side of the pulley. The first video linked below describes how to think through a traditional “modified Atwood's machine".

See below for other videos related to forces and motion.

Finding Acceleration and Tension for a "Modified Atwood's Machine":    • Finding Acceleration and Tension for ...  

Force Diagrams and Component Forces:    • Video  
Force Diagrams on Inclines:    • Video  
Quantitative Force Diagrams:    • Quantitative Force Diagrams  
Exploring Static and Kinetic Friction:    • Exploring Static and Kinetic Friction  
Static and Kinetic Friction Examples:    • Static and Kinetic Friction Examples  
Symbolic Problem Solving with Friction on Inclines:    • Symbolic Problem Solving with Frictio...