Bennett Mechanical Comprehension Practice Test

A seesaw is classified as a first class lever because it features a fulcrum positioned between the effort and the load. In this type of lever, when force is applied on one side, it causes the other side to lift. The arrangement allows for a balance of forces where children sitting at either end can move up and down, demonstrating the principle of leverage. This configuration is the defining characteristic of first class levers, where the input force, output force, and fulcrum are strategically placed to create mechanical advantage.

In contrast, second class levers have the load positioned between the effort and the fulcrum, while third class levers feature the effort applied between the load and the fulcrum. An inclined plane, which is an entirely different machine class, involves sloping surfaces to reduce the amount of force needed to raise an object. Hence, the seesaw’s design and function distinctly identify it as a first class lever.