What type of simple machine is a lever?

A lever is classified as a simple machine that consists of a rigid bar that pivots around a fixed point known as the fulcrum. This design allows the lever to amplify force, making it easier to lift or move objects. The position of the fulcrum can significantly affect the mechanical advantage gained when the lever is used, depending on how far the effort and load are from the fulcrum. This principle of leveraging force is essential in a variety of applications, from everyday tasks to complex machinery.

The other options describe different types of simple machines. A wheel and axle is designed to facilitate rotational movement and reduce friction, an inclined plane (the flat surface) assists in raising objects by extending the distance over which the load is lifted, and a curved surface is characteristic of a wheel or a ramp that enables rolling. Each serves a distinct purpose but does not represent the characteristics of a lever.