The shoulder of power. The condition of equilibrium of the lever

The shoulder of the force $l$ is the distance from the center of the lever to the point of application of the force. The lever rule, or the lever balance condition, can be written with a formula

F_{1} \cdot l_{1} = F_{2} \cdot l_{2}

The balance condition of a lever says that if one force arm of the lever is a certain number of times longer than the other, then the same number of times less force can be applied to it, so that the lever remains in balance.