Levers

Class 1, Class 2, Class 3

Class one

  • Class 1: Fulcrum in the middle: the effort is applied on one side of the fulcrum and the resistance on the other side, for example, a crowbar, or a pair of scissors

Class Two

Class 2: Resistance in the middle: the effort is applied on one side of the resistance and the fulcrum is located on the other side, for example, a wheelbarrow, or a nutcracker. The mechanical advantage is greater than class one.

Class Three

Class 3: Effort in the middle: the resistance is on one side of the effort and the fulcrum is located on the other side, for example, the human arm. The mechanical advantage is less than class one.

The Law of Equilibrium.

A lever is in equilibrium when the effort and the load balance each other. The law of equilibrium is: The effort multiplied by its distance from the fulcrum equals the load multiplied by its distance from the fulcrum. This law of equilibrium is true for all classes of levers.