Waves and Sound (7)

Transverse Waves

have oscillations of wave particles perpendicular to the direction of wave propagation (e.g, "The Wave”, electromagnetic waves)

Longitudinal Waves

have oscillations of wave particles parallel to the direction of wave propagation (e.g., sound waves)

Displacement (x)

in a wave refers to how far a point is from the equilibrium position, expressed as a vector quantity

Amplitude (A)

of a wave is the magnitude of its maximal displacement

Crest

maximum point of a wave (point of most positive displacement)

Trough

minimum point of a wave (point of most negative displacement)

Wavelength (lambda)

of a wave is the distance between two crest cells or two troughs

Frequency (F)

of a wave is the number of cycles it makes per second. It is expressed in hertz (Hz)

Angular Frequency

is another way of expressing frequency and is expressed in radians per second

Period (T)

of a wave is the number of seconds it takes to complete a cycle. It is the inverse of frequency

Interference

describes the ways in which waves interact in space to form a resultant wave

Constructive Interference

occurs 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

occurs when waves are exactly out of phase with each other. The amplitude of the resultant wave is equal to the difference in amplitude between the two interfering waves

Partially Constructive and Partially Destructive Interference

occur when two waves are not quite perfectly in or out of phase with each other. The displacement of the resultant wave is equal to the sum of the displacements of the two interfering waves

Traveling Waves

have continuously shifting points of maximum and minimum displacement

Standing Waves

are produced by the constructive and destructive interference of two waves of the same frequency traveling in opposite directions in the same space

Antinodes

are points of maximum oscillation

Nodes

are points where there is no oscillation

Resonance

is the increase in amplitude that occurs when a periodic force is applied at the natural (resonant) frequency of an object

Damping

is a decrease in amplitude caused by an applied or nonconservative force

Sound

is produced by mechanical disturbance of a material that creates an oscillation of the molecules in the material

Solids, Liquids, Gases

sound propagates fastest through _________, followed by __________, and slowest through ___________

Decreases

within a medium, as density increases, the speed of sound ________

Pitch

of a sound is related to its frequency

Doppler Effect

is 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

Higher

the apparent frequency will be ________ than the emitted frequency when the source and detector are moving toward each other

Lower

the apparent frequency will be ________ than the emitted frequency when the source and detector are moving away from each other

Higher, Lower, or Equal to

the apparent frequency can be ________ to the emitted frequency when the two objects are moving in the same direction, depending on their relative speeds

Shock Waves (Sonic Booms)

when the source is moving at or above the speed of sound, this can form

Intensity

loudness or volume of sound (sound level) is related to this. This is also related to a wave 's amplitude. This decreases over distance and some energy is lost to attenuation (damping) from fictional forces

Open Pipes

strings and this support standing waves, and the length of the string or pipe is equal to some multiple of half-wavelengths

Closed Pipes

support standing waves and the length of the pipe is equal to some odd multiple of quarter-wavelengths

Ultrasound

sound is used medically in ________ machines for both imaging (diagnostic) and treatment (therapeutic) purposes