How can you identify a wheel and axle?

A wheel and axle are identified by their fundamental design, which consists of a large wheel connected to a smaller axle, allowing both components to rotate together. This configuration is specifically designed to amplify either force or speed, depending on how it is applied.

When a force is applied to the wheel, it can enable the axle to turn with greater efficiency, which is a principle exploited in various machines such as cars and bicycles. The larger diameter of the wheel allows for easier movement by applying a smaller input force, which is then transmitted through the axle to perform work, often resulting in increased speed or reduced effort.

The other options describe elements that do not fit the definition of a wheel and axle. A single rotating disc serving as a lever does not encompass the dual-component nature of a wheel and axle system. Interlocked gears refer to mechanisms designed for different purposes, usually involving rotational motion but not fitting the wheel and axle description. Finally, a fixed point where levers rotate describes a fulcrum, which is distinct from the rotational and structural characteristics of a wheel and axle. Thus, the essential characteristic of the wheel and axle as a tool for amplifying force or speed is clearly captured in the first option.