Name a real-world application of the wheel and axle.

A bicycle wheel is a perfect illustration of the wheel and axle system in real-world applications. This simple machine consists of a large wheel attached to a smaller axle, allowing for efficient movement and the ability to carry heavier loads with less effort. When the wheel turns, it rotates the axle, which in turn drives the bicycle forward. This setup reduces friction compared to walking, making it easier to travel over distances.

The design of the bicycle wheel allows for significant mechanical advantage; as the wheel rolls, it converts the energy from pedaling into forward motion more effectively than if one were just trying to walk or push a load directly. The larger the wheel, the farther it can travel with a single rotation, illustrating how this simple machine improves transportation efficiency. Other options, such as a lever, ramp, or pulley system, represent different types of simple machines with distinct functions, but they do not utilize the wheel and axle mechanism.