And probably the rest of the lessons I missed. We were asked to research stability and equilibrium. So far, I know that equilibrium is a state an object is in when no unbalanced forces are acting upon it. http://www.physicsclassroom.com/Class/vectors/U3L3c.html I got lost when I read after the scale diagram. I searched some more and I found some problems (1. An object acted on by three forces moves with constant velocity. One force acting on the object is in the positive x direction and has a magnitude of 6.5 N; a second force has a magnitude of 4.4 N and points in the negative y direction. Find the magnitude of the third force acting on the object. http://www.physics247.com/physics-homework-help/simple-equilibrium.php) that I really had no idea how to solve because all I knew was that equilibrium was that balance! So could someone please help me understand? I know it looks like I haven't tried hard enough but I really did. Don't be mad.