Mechanical Advantage of Pulleys

To investigate the mechanical advantage of pulleys.

Definition and Theory
A single pulley is used to change the direction of the pull to lift a load. A system of pulleys is used to lift heavy loads by the mechanical advantage of increasing the length of travel of the pull and decreasing the load. The mechanical advantage of a system of pulleys is equal to the number of ropes that support the moveable pulley, less any friction on the pulley. The amount of friction is the difference between the actual load measured and the calculated load.

  • P = Load (number of pennies)
  • P(actual) = Actual Load
  • P(calc) = Calculated Load
  • N = Number of Ropes
    (Mechanical Advantage)
  • P = Pa x N
  • F = Friction
  • F = P(actual) - P(calc.)


Laboratory Worksheet