A lever is a simple device or machine.  It can be used to gain a mechanical advantage. Levers are found in all kinds of places.

The first class lever is also known as a rocker arm. When one end of the lever is pressed, the other end of the lever rises. The force and the load move in different directions. The fulcrum, or the part of the lever that provides it with support, is located at the center of the lever.

Pressing a first class lever requires a broad hand movement, but it also requires less force. The closer the load is to the fulcrum and the longer the lever is, the easier it is to lift the load. 

A rocker arm is useful for twisting containers and cans open. Bottle openers also make use of the first class lever.


A rocker arm is useful for opening various containers.

Soda cans are also opened with small first class levers. The force of your fingers lifts one end of the lever. The rivet at the center of the opener acts as the fulcrum. The other end of the lever is pressed downwards and opens the can.

If a glass jar contains a vacuum, it may be hard to open. This is when a rocker arm becomes useful. It can be used to lift the lid of the jar so that air is able to fill the jar. After this, the jar is easier to open.


Image on the left: Soda cans are opened with simple first class levers. Image on the right: If a glass jar contains a vacuum, the lid can be opened with the help of a rocker arm. 

The see-saws found in playgrounds are also first-class levers. The function of old draw-wells also makes use of a rocker arm.


See-saws and draw-wells are examples of first class levers.