1. Torque and Static Equilibrium Torque: Let F be a force acting on an object, and let r be a position vector from a chosen point O to the point of application of the force. The magnitude of the torque  exerted by the force F is given by  rFcos  Units: Newton-meter (Nm)

2. Torque is a vector. So we need a way to determine the direction of the torque. 1.Point your fingers in the direction of r. 2.Curl your fingers in the direction of F. 3.Your thumb will point in the direction of the torque. Right-hand Rule

4. Static Equilibrium There are two conditions for static equilibrium: 1.The net external force must be zero 1.The net external torque must be zero