The formula for force of friction (F_f) is the same whether kinetic or static friction applies: F_{f =} μF_N. To distinguish between kinetic and static friction, μ_k and μ_s are often used in place of μ.

Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.

An inclined plane is a simple machine that reduces the force needed to raise an object to a certain height. Work equals force x distance and, by increasing the distance that the object travels, an inclined plane reduces the force necessary to raise it to a particular height. In this case, the mechanical advantage is to make the task easier. An example of an inclined plane is a ramp.

Normal force (F_N) represents the force a surface exerts when an object presses against it.