SPHHRNG 3340 Chapter Notes - Chapter 2: Sine Wave, Infrasound, Hearing Range
14 Mar 2018
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Vibrations general notes, sound begins with vibrations, vibration: motion that is back and forth, can be as simple as a pendulum swinging or as complicated as a car"s glove, mass and spring box on a bumpy road. Simplest possible system"s vibration - simple harmonic motion: most fundamental vibrator = single mass hanging from a spring. If no motion; force of gravity pulling the mass down is balanced by force of spring pulling up - mass is at rest: this is equilibrium, mass being at equilibrium means displacement is zero. Since it isn"t moving it hasn"t moved at all from its original position. If mass moves above equilibrium position displacement is positive, if down then it"s negative. Frequency (f) = 1/t (period) where f is in hertz: phase lead-phase lag. If two sine waves have the same frequency but different starting phases, one leads or lags the other one. Lagging wave : x(t) = a sin(360 f* t)
