Accoustics [PC120]

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The Metric System

Ex. 1,000 m = 1 km

conversions:

        

                X = 0.52 m

Simple Harmonic Motion

  1. Periodic
  1. phenomenon repeats itself
  2. period = amount of time to repeat (T)
  3. ex. rotation of the earth T = 1 day

  1. Motion has a stable equilibrium
  1. equilibrium point = position of natural rest
  2. stable = if displaced from equilibrium, it will return to equilibrium point

  1. Stability of equilibrium is caused by a linear restoring force
  1. restoring force = force that pushes towards equilibrium point
  2. linear = force is proportional to distance displaced
  3. ex. 10 N of force is applied to a spring to displace it 4 meters.

        20 N of foce is needed to displace it 8 meters. ETC.

Describing Simple Harmonic Motion

period : time it takes to complete one oscillation                (T)

Amplitude : max distance displaced from equilibrium         (A)

Frequency = # of cycles per second                         (f)

  and  

example : T = 0.25  

 Therefore f = 5 Hz

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Trigonometry

                 

                 

phase : an angle that tells us how much a wave has shifted

        θ = degree of phase difference