Resolving Forces On A Rigid Body
Resolving the forces on an object is similar to resolving forces on a particle, because an object has a physical size this means for it to be in static equilibrium it needs to also have no net rotational forces. This is where the sum of moments about a point becomes very important.
The sum of all the moments about any point on an object in static equilibrium is always equal to 0
for a worked example, click here