# Equilibrium, Torque, and Energy

 static equilibrium zero velocity dynamic equilibrium velocity is not zero Is equilibrium motionless? NO! just, some of all forces acting on the system = 0 straight acceleration (not in equilibrium) What is the equation? ∑F = ma 1. write equation as if sys. were in equilibrium2. add "ma" to side with less force Example: Fdown due to gravity Fup due to air resistance Fdown > Fup, so Fdown = Fup + ma What does this mean? In order to be in equilibrium Fup must be increased by ma Torque (equation) t = F x r x sin Torque (equilibrium) 0 net torque Tclockwise = Tcounter-clockwise static equilibrium Fup = Fdown If force is at the point of rotation, what is the torque? 0 board hanging on a string, in equilibrium F = mass of the board at the center of mass Units of energy (J) for macroscopic sys(eV) microscopic sys forms of mechanical energy kinetic energypotential energy What is kinetic energy? What is the equation for kinetic energy? energy of motion 1/2 mv2 Authornatalieplana ID68782 Card SetEquilibrium, Torque, and Energy DescriptionPhysics Lecture 3 Updated2011-02-25T01:55:37Z Show Answers