Explanation:
The wheel and axle is classified as one of the six simple machines (the other five are the lever, pulley, inclined plane, wedge and screw). We use simple machines because they give us a mechanical advantage. For example, we can carry more in weight by pushing a cart on wheels than holding it in our arms.
The axle and wheel are two circles, and they rotate together. Force is usually transferred from the axle to the wheel. The mechanical advantage of the wheel and axle is essentially the ratio of the radius of the wheel over the radius of the axle.
Remember that the radius of a circle is half its diameter.
Radius of wheel and axle
The ratio of the radii of the wheel and axle gives you the mechanical advantage.
Mechanical Advantage of Wheel and Axle
