Statics: How to Calculate a Force’s Moment
In statics, moments are effects (of a force) that cause rotation. When computing equilibrium, you must be able to calculate a moment for every force on your free-body diagram. To determine a force’s moment, you use one of two different calculations, as you can see in the following list.
Scalar calculation (for two dimensions): To calculate the moment about a Point O in scalar calculations, you need the magnitude of the force and the perpendicular distance from Point O to the line of action of the Force F.
Vector calculation (for two or three dimensions): To compute the moment vector about a Point O in vector calculations, you must determine the Force F in Cartesian vector form and the position vector from Point O to the line of action of the Force F.