Which simple machine's mechanical advantage is calculated using the ratio of the radius of the wheel to the radius of the axle?

The mechanical advantage of a wheel and axle is calculated using the ratio of the radius of the wheel to the radius of the axle because this reflects how force is distributed when using this type of simple machine. The wheel and axle configuration allows for easier movement of loads by amplifying the input force through the ratio of these two radii.

In this system, when you apply a force to the wheel, that force is transferred to the axle. The larger radius of the wheel compared to the axle means that a smaller force applied over a larger distance on the wheel translates into a larger force exerted over a smaller distance on the axle, thus enabling the movement of heavier loads more efficiently. This principle of using the ratio of the radii allows for an understanding of how effectively the simple machine can transform input force into output force.

In contrast, while pulleys, levers, and inclined planes operate on different principles of mechanical advantage, they do not utilize the ratio of two radii in their calculations, making the wheel and axle unique in this specific aspect.