1-4 Sinusoidal traveling waves

The frequency is the number of periods (oscillations) in one unit of time.
 For example, f = 2.5 Hz means that there are 2.5 periods in one second.
 The SI unit for the frequency is the Hertz (Hz).

The angular frequency is the number of periods (oscillations) in a 2p unit of time.
For example, w = 5.2 rad/s means that there are 5.2 periods in 2p seconds.
The SI unit for the angular frequency is radians per second (rad/s).

The angular wave number is the number of wavelengths in a 2p unit of distance.
For example, k = 2.3 rad/m means that there are 2.3 wavelengths in 2p meters.
The SI unit for the angular wave number is radians per meter (rad/m).