Physics and Math Chapter 7: Waves and Sound Flashcards
Transverse waves
Have oscillations of wave particles perpendicular to the direction of wave propagation.
Longitudinal waves
Have oscillations of wave particles parallel to the direction of wave propagations
Displacement
Refers to how far a point is from the equilibrium position
Amplitude
Magnitude of its maximal displacement
Crest
the maximum point of a wave (point of most positive displacement)
Trough
the minimum point of a wave (most negative displacement)
Wavelength
the distance between two troughs or two crests
Frequency
The number of cycles it makes per second. (Hz)
Angular frequency
frequency in radians per second
Period
number of seconds it takes to complete a cycle (inverse of frequency
Interference
The ways in which waves interact in space to form a resultant wave.
Constructive interference
when waves are exactly in phase with each other. The amplitude of the resultant wave is equal to the sum of the amplitudes of the two interfering waves
Destructive interference
waves are exactly out of phase. resultant is equal to the difference in amplitude between the two interfering waves
Partially constructive and partially destructive
occur when 2 waves are not quite perfectly in or out of phase. the displacement is equal to the sum of the displacements of the two interfering waves
Traveling waves
have continually shifting points of maximum and minimum displacement
Standing waves
produced by the constructive and destructive interference of two waves of the same frequency traveling in opposite directions in the same space.
Antinodes
points of maximum oscillation
Nodes
points where there is no oscillation
Sound
produced by mechanical disturbance of a material that creates an oscillation of the molecules in the material.
resonance
the increase in amplitude that occurs when a periodic force is applied at the natural resonant frequency of an object
Damping
decrease in amplitude caused by an applied or nonconservative force
What can sound not propagate through?
Vacuum
What does sound propagate the fastest through?
Fastest - Solids
Liquids
Slowest - Gases
As density increases, the speed of sound…
decreases
pitch
related to frequency
Doppler effect
a shift in the perceived frequency of a sound compared to the actual frequency of the emitted sound when the source of the sound and its detector are moving relative to one another.
When source and the detector are moving towards each other…
Apparent > emitted
When source and detector are moving away from each other…
Apparent
When source and detector are moving in the same direction…
Apparent can be or =, depending on the relative speeds
Shock waves
When the source is moving at or above the speed of sound — can form shock waves
Intensity
Loudness or volume of sound related to a wave’s amplitude
Intensity over distance
Intensity decreases over distance – some energy is lost to attenuation from frictional forces
Strings and open pipes
support standing waves and the length of the string or pipe is equal to some multiple of half-wavelengths
Closed pipes
also support standing waves and the length of the pipe is equal to some odd multiple of quarter-wavelengths
How is sound used medically?
In ultrasounds
