Definition:Line of Action

Definition
Let a force $\mathbf F$ act on a rigid body $B$.

In order to completely specify how $\mathbf F$ acts on $B$, it is necessary to know the point $P$ on $B$ at which $\mathbf F$ is applied.


 * Line-of-action.png

The (straight) line $L$ passing through $P$ in the direction of $\mathbf F$ is known as the line of action of $\mathbf F$ on $B$.