2D Couple
Description
This applet illustrates a couple. A couple is two forces applied a distance apart. One force is the negative of the other force.
In this applet you can control the application points for the two forces (A and B) and the force vector is controlled by the triangular point F.
Three calculations can be shown of the net moment of the two forces.
"About B" shows the calculation of the moment about point B where the moment due to the negative force is zero.
"Perpendicular Distance" shows the perpendicular distance times the magnitude of the force vector. Whether the moment is positive or negative can be determined from the right hand rule.
"Other Point" adds a point C where the sum of the two moments can be calculated about.
Observe how the moment changes as you move point C.