Vibration:An oscillation, or repeating back-and-forth motion, about an equilibrium position.
Wave: A "wiggle in space and time"; a disturbance that repeats regularly in space and time and that is transmitted progressively from one place to the next with no actual transport of matter.
Wave period: A few seconds between waves
Crest: 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 the crest.
Amplitude: The distance from the midpoint to the maximum (crest) of a wave or, equivalently, from the midpoint to the minimum.
Wave Length: 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 events) per time; measured in hertz ( or events per time)
Hertz: The SI unit of frequency. One hertz is one vibration per second.
Transverse wave: A wave with vibration at right angles to the direction the wave is traveling.
Longitude Waves: A wave in which the vibration is in the same direction as that in the same direction as that in which the wave is traveling, rather than at right angles to it.
Doppler Effect: The change in frequency of a wave due to the motion of the source or the the receiver
Blue shift: An increase in the measured frequency of light from an approaching source; called the blue shift because 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 from a receding source; called the red shift because the decrease is 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 the listner.