Creative Commons License Copyright © Michael Richmond. This work is licensed under a Creative Commons License.

A problem which is easy if you use phasors

Joe sets up three tuning forks on the table in front of him. Each tuning fork has exactly the same frequency: 440 Hz. However, the forks are different sizes:

  1. tiny fork produces a wave with amplitude 2 units
  2. middle fork produces a wave with amplitude 6 units
  3. big fork produces a wave with amplitude 10 units

Joe strikes the tuning forks with his rubber mallet. Even though he tries to strike them all at once, there is a small offset in the production of each wave.

  1. tiny fork has phase phi = 0
  2. middle fork has phase phi = 90 degrees
  3. big fork has phase phi = 180 degrees 



       Q:  What is the amplitude of the combined wave produced
              by all three forks?  


       Q:  What is the phase of the combined wave produced
              by all three forks, relative to the 
              wave of the tiny fork?

Creative Commons License Copyright © Michael Richmond. This work is licensed under a Creative Commons License.