Vocabulary
The sound produced as a result of an object traveling at or above Mach 1
Sonic boom
What is the speed of sound in air that has a temperature of 20 degrees Celsius?
v= (331.5 + 0.6 x 20) m/sec
V= (331.5 + 12) m/sec
v= 343.5 m/sec
(v stands for speed)
The highest points on a wave
the crest
A battleship blows its horn. Some of the sound waves travel through the air and then hit the water. Will the sound waves travel faster in the air or in the water?
Water
Sound waves travel faster in liquid than they do in gases.
Any speed that is faster than the speed of sound in the substance of interest
Supersonic speed
A sound wave traveling through 19 degrees Celius air has a wavelength of 2 meters. What is the frequency of the sound wave?
Speed- v= (331.5 + 0.6 x 19) m/sec
v= (341.7) m/sec
Frequency- 341.7 m/sec / 2m (divide)
f= 170.85 Hz
The lowest point points of a wave
Troughs
Which waves have the longest wavelength: sonic waves, infrasonic waves, or ultrasonic waves?
Infrasonic waves
Infrasonic waves have the lowest frequencies, sonic waves have the higher frequencies, and ultrasonic waves have the highest frequencies. Since frequency and wavelength are inversely proportional, infrasonic waves have the longest wavelength
An indication of how high or low a sound is, which is primarily determined by the frequency of the sound wave
Pitch
During a thunderstorm, the temperature is 10 degrees Celsius. If you see a lightning strike and then hear the thunder 2 seconds later, how far away did the lightning strike?
Speed- v= (331.5 + 0.6 x 10) m/sec
v= 337.5 m/sec
distance traveled= (337.5 m/sec) x (2 sec) = 675 m
The distance between the crest (or the distance between the troughs)
Wavelength
The change in frequency of a wave as observed by someone moving relative to the source of the wave. It commonly explains why a siren sounds higher in pitch as it approaches and lower as it moves away.
The Doppler effect
A wave with a direction of progagation that is perpendicular to the direction of oscillation
Transverse wave
A jet travels through 10 degrees Celsius air at Mach 3. What is its speed in meters per second?
=1,012.5 m/sec
v= (333.5 + 0.6 x 10) m/sec
v=337.5 m/sec
Since sound travels at 337.5 m/sec, Mach 3 is 3 x (337.5 m/sec) = 1,012.5 m/sec
The height of the wave
Amplitude
The substance or material that allows the transmission or propagation of energy, force, or information from one point to another. This can be solids, liquids, gases, or even electromagnetic waves.
a medium
Sound waves cannot travel if there is no medium for them to oscillate.
A wave with a direction of propagation that is parallel to its direction of oscillation
Longitudinal wave
The sound from a typical vacuum cleaner is about 60 decibels, while the sound of a rifle firing is about 140 decibels. How many times larger is the intensity of the waves coming from the rifle as compared to those coming from the vacuum cleaner?
100,000,000 times larger
The rifle is 8 bels louder than the vacuum cleaner. Since each bel unit represents a 10-fold increase in sound wave intensity, the total increase is calculated by taking 10 and multiplying it by itself 8 times. 10x10x10x10x10x10x10x10= 100,000,000
The unit for frequency
Hertz
Do sound waves oscillate parallel to or perpendicular to the direction in which the wave travels?
Parallel
Sound waves are longitudinal waves. This means they oscillate parallel to the direction in which they travel.