vibration: an oscillation, or repeating back-and-forth motion, about an equilibrium position.
wave: a disturbance that repeats regularly in space and time and that is transmitted progessively from one place to the next with no actual transport of matter.
wave period: a wiggle in space and time
crests: one of the places in a wave where the wave is highest or the disturbance is greatest.
troughs: one of the places in a wave where the wave is lowest , or the disturbance is greatest, in the opposite direction from a crest.
amplitude:the distance from the midpoint to the maximum (crest) a wave, or equivalently, from the midpoint to the minimum (trough)
wavelength: the distance from the top of the crest of a wave to the top of the following crest, or equivalently, the distance between successive identical parts of the wave.
frequency: the number of events ( cycles, vibrations, oscillations, or any repeated event) per time; measured in hertz ) or events per time). Inverse of period.
hertz: the SI unit of frequency. One hertz (Hz) is one vibration per second.
transverse waves: a wave with vibration at right angles to the direction the wave is traveling.
longitudinal waves: a wave in which the vibration is in the same direction as that in which the wave is traveling, rather then at right angles to it.
Doppler Effect: the change in frequency of a wave due to the motion of the source or of the receiver.
blue shift: an increase in the measured frequency of light from an approaching source: called the blue shift because the apparent increase is toward the high-frequency, or blue, end of the color spectrum. Also occurs when an observer approaches a source.
red shift: a decrease in the measured frequency of light (or other radiation) from a receding source; called the red shift because the decrease is toward the low-frequency, or red, end of the color spectrum.
shock wave: a cone-shaped wave produced by an object moving at supersonic speed through a fluid.
sonic boom: the sharp crack heard when the shock wave that sweeps behind a supersonic aircraft reaches tje listener.