Period motion / oscillation = back and forth motion. Body that undergoes periodic motion always has a stable equilibrium position it tends towards. Restoring force = the spring force that tends to restore it to the equilibrium position. Origin is at the equilibrium position: is -component of displacement. Amplitude ( ) = maximum magnitude of displacement from equilibrium. Period ( ) = time to complete one cycle. Frequency ( ) = number of cycles in a unit of time. Angular frequency ( ) = times the frequency. Simple harmonic motion = when the restoring force is directly proportional to the displacement from equilibrium. Picture a disk rotating with constant angular speed with a ball attached. Harmonic oscillator = a body that undergoes simple harmonic motion. Uniform circular motion is related to simple harmonic motion casts shadow of ball on screen. Shadow at point p oscillates as ball moves in circle.
