This week’s equation of the week is the friction equation.

Notice that this equation does not contain vector symbols. The friction force is parallel to the surface. The normal force is perpendicular to it. However, as you push harder on the surface, the frictional force becomes proportionally larger.

The constant in this equation, *μ* (Greek letter mu), is known as the coefficient of friction. It varies between zero and two. A frictionless surface would have *μ* = 0. The larger the *μ*, the more friction there is.

To learn more about this equation, visit our lesson on the friction equation.