Equivalent Force

This is a concept used for equivalent systems to help us more easily solve problems.

Systems $S_1$ and $S_2$ are equivalent if:

$(\sum \overline{F}{)}_1=(\sum \overline{F}{)}_2$ $(\sum {\overline{M}}_P{)}_1=(\sum {\overline{M}}_P{)}_2$ P can be any common point on $S_1$ and $S_2$

We then go a step further and try to make a Resultant Force