Mechanical Advantage in Sport (AQA GCSE Physical Education (PE)): Revision Note

Mechanical Advantage in Relation to the Three Lever Systems

• Different types of levers in the human body offer different mechanical advantages, enhancing efficiency and effectiveness in different types of movement

• First and third class levers have an effort arm that is short compared to the resistance arm

  • This enables:

    • Fast movement

    • A wide range of movement

  • E.g. the biceps acting to pull up the lower arm around the elbow joint as an example of a third class lever

Mechanical advantage in first and third class levers diagram

In a first and third class lever the effort arm is shorter than the resistance arm

• Second class levers have a long effort arm compared to the length of the resistance arm

  • This allows joints to overcome a large resistance with relatively little effort

  • E.g. the gastrocnemius muscle acting to lift body weight around the ankle joint as a fulcrum

Mechanical advantage in second class levers diagram

In a second class lever the effort arm is longer than the resistance arm

Calculating mechanical advantage

• We can calculate the mechanical advantage by measuring the length of the effort arm and the resistance arm and applying the following equation

mechanical advantage = effort arm length ÷ weight (resistance) arm length