What are 1st, 2nd and 3rd class levers?

The first class lever uses the fulcrum in between the applied force and load, the second class lever uses the load between the fulcrum and applied force and the third class lever uses the applied force between the fulcrum and the load. Levers help to lift heavy objects.

Levers are one of the simplest machines. An example of a first class lever is a seesaw or balance beam, an example of a second class lever is a wheelbarrow and an example of a third class lever is the human forearm. In the human forearm, the elbow acts as the fulcrum, the applied force is the bicep muscle and the hand acts as the load.