Principle of Lever

Physical Law

$\operatorname{MA} = \dfrac {F_B} {F_A} = \dfrac a b$

where:

$\operatorname{MA}$ is the mechanical advantage of the lever
$F_A$ is the force applied to the lever at point $A$
$F_B$ is the resulting force that the lever applies at point $B$
$a$ and $b$ are the distances from the fulcrum to points $A$ and $B$.

Historical Note

The principle of the lever was discovered by Archimedes of Syracuse.