Mechanical Waves

Harmonic Motion What makes things oscillate? Work = Force * distance Consider extended spring: Stored energy release spring --> oscillation Motion oscillates between stored energy and energy of motion ==> transfer of energy constant K depends on spring material Time for 1 cycle : T [period] Frequency: Unit is Hertz : [Hz] = [1/s] named after Heinrich Hertz (1857 - 1894); University of Bonn (Germany) See the animation Circles and Sine Waves. REVIEW Why do things oscillate? There is a restoring force F = -kx Energy is stored. Recall: Energy = Work = F d Oscillation results from energy transfer. stored energy --> Energy of motion Energy of motion --> stored energy Period T : time for one full cycle frequency f: f = 1/T Example: An oscillator takes 0.1 s for 1 cycle. --> f = 1 / 0.1 s = 10 Hz

Ch. Elster
Aug 26 14:27:03 EDT 2019