6th Grade Science Chapter 2 Sound

35 terms

longitudinal wave (compression waves)

a wave in which the matter moves back and forth parallel to the direction of the wave

sound waves

these travel as vibrations moving through the air and other mediums as a compressional wave

seismic waves

An energy wave which vibrates through the earth's crust as the crust bends or breaks

crest

the highest point on a transverse wave

trough

the lowest point on a transverse wave

node

The rest position of the wave

wavelength

the distance from one point on the wave to the next corresponding adjacent point

compression

the areas of a wave that are squeezed together

rarefaction

The areas of a wave that are spread out

compressional longitudinal wave length

the distance from the center of one compression to the center of the next compression

wave frequency

the number of waves that pass through a point in one second

hertz (Hz)

The unit for frequency is waves per second

frequency

the number of waves(vibrations) that pass through a point in one second

period

the time it takes for one full wavelength to pass a certain point

wave speed

A wave moving through a medium travels at a certain speed. It is calculated as the product of a waves frequency and wavelength.

wavelength is represented by:

the Greek letter lambda (λ)

(f)

amplitude of a compressional wave

is determined by the closeness of the waves. The closer the waves the farther the rarefaction lines

amplitude of a transverse wave

determined by the height of the crest or depth of the trough

reflection

When a wave bounces off an object and changes direction

refraction

the bending of a wave as it passes from one medium to another

diffraction

occurs when an object causes a wave to change direction and bend around it. Also occurs when passing through a small opening

constructive interference

the interference of two or more waves of equal frequency and phase, resulting in their mutual reinforcement and producing a single amplitude equal to the sum of the amplitudes of the individual waves

destructive interference

the interference of two waves of equal frequency and opposite phase, resulting in their cancellation where the negative displacement of one always coincides with the positive displacement of the other

resonance

occurs when a sound wave has the same frequency as the natural frequency of an object. The sound will cause the object with the same natural frequency to vibrate

intensity

the energy that the sound wave possesses. The greater the intensity of sound the farther the sound will travel and the louder the sound will appear

loudness

the human perception of the sound intensity

decibels

the unit used to express the intensity of a sound

pitch

the degree of height or depth of a tone or of sound, depending upon the relative rapidity of the vibrations by which it is produced.

frequency

the number of cycles or completed alternations per unit time of a wave

infrasonic

sounds below 20 Hz

ultrasonic

sounds above 20,000 Hz

Doppler Effect

the apparent change in frequency detected when the sound is moving relative to the hearer

acoustics

the study of sound and ways to optimize the hearing of sound inside various structures

sonar

a system that uses the reflection of underwater sound waves to detect objects. This has been used to find sunken ships and schools of fish