Here's a demo that shows the nearly sinusoidal waveforms
produced by two clay whistles.
PhasorRaces began as a speed drill for testing complex addition.
Now it includes many other related operations that can be tested
in a "drill" scenario: adding sinusoids, z-transforms, etc.
A timer starts as soon as the problem is posed, so that a
student can try to solve questions quickly and accurately.
Here are four movies showing rotating phasors and
how the real part of the phasor traces out a sinusoid
Two of the movies show how rotating phasors of
different frequencies interact to produce complicated
waveforms such as beat signals.
Sine Drill (sindrill) is a program that tests the users ability to determine
basic parameters of a sinusoid.
After a plot of a sinusoid is displayed, the user must correctly
guess its amplitude, frequency, and phase.
This is an introduction to plotting sinusoids (both sine
and cosine waves) from equations.
The tutorial also reviews how to write the
equation of the sinusoid given a plot of the waveform.
This demo shows how the size and stiffness of
a tuning fork affect the tone produced by
three different tuning forks.
ZDrill is a program that tests the users ability to calculate the result
of simple operations on complex numbers.
The program emphasizes the vectorial view of a complex number.
The following six operations are supported: