A pulley is a simple machine having a string that passes over a grooved wheel. A fixed pulley is attached to a solid support and changes the direction of force. Resistance force, the weight of an object being lifted, is attached to one end of the string going over the fixed pulley. Effort force is exerted downward on the other end of the string to lift the object upward.

A movable pulley moves along the string with the resistance force, and the direction of the force is not changed. That is, the Effort Force is upward and the object is lifted upward. A pulley system may have a single pulley or a combination of pulleys. Pulley systems are used to make work easier.

Mechanical advantage is a value that tells the number of times a machine increases the applied force. In this experiment, you will use the force sensor built into a Sensor Cart to measure the effort force for three different pulley systems and then determine the mechanical advantage of each system.


  • Measure force.
  • Calculate actual mechanical advantage (AMA).
  • Determine ideal mechanical advantage (IMA).
  • Calculate efficiency.
  • Make conclusions about pulley systems.