Chapter 13 - Waves and Sound
wave
A disturbance or vibration propagated from point to point in a medium or in space
natural frequency
A frequency at which an elastic object naturally tends to vibrate, so that minimum energy is required to produce a forced vibration or to continue vibrating at that frequency
sound wave
A longitudinal vibratory disturbance that travels in a medium, which can be heard in the approximate frequency range 20-20,000 Hz
beats
A series of alternate reinforcements and cancellations produced by the interference of two waves of slightly different frequency, heard as a throbbing effect in sound waves
standing wave
A stationary wave pattern formed in a medium when two sets of identical waves pass through the medium in opposite directions
longitudinal wave
A wave in which the medium vibrates in a direction parallel to the direction in which the wave travels
transverse wave
A wave in which the medium vibrates in a direction perpendicular to the direction in which the wave travels. Light is an example
frequency
For a vibrating body or medium, the number of vibrations per unit time. For a wave, the number of crests that pass a particular point per unit time
amplitude
For a wave or vibration, the maximum displacement on either side of the equilibrium (midpoint) position
hertz
The SI unit of frequency. It equals one vibration per second
bow wave
The V-shaped wave produced by an object moving across a liquid surface at a speed greater than the wave speed
refraction
The bending of a wave through either a non-uniform medium or from one medium to another, caused by difference in wave speed
Doppler effect
The change in frequency of wave motion resulting from motion of the wave source or receiver
shock wave
The cone-shaped wave created by an object moving at supersonic speed through a fluid
wavelength
The distance between successive crests, troughs, or identical parts of a wave
sonic boom
The loud sound resulting from the incidence of a shock wave
interference
The pattern formed by superposition of different sets of waves that produces mutual reinforcement in some places and cancellation in others
wave speed
The speed with which waves pass a particular point: _________ = frequency x wavelength
resonance
The response of a body when a forcing frequency matches its natural frequency
forced vibration
The setting up of vibrations in an object by a vibrating force
period
The time required for a vibration or a wave to make a complete cycle; equal to 1/frequency