Mod. 14 (Sound Waves) Test

Front 1

Pitch

Back 1

an indication of how high or low a sound is, which is primarily determined by the frequency of the sound wave

Front 2

longitudinal wave

Back 2

A wave with a direction of propagation (travelling) that is parallel to its direction of oscillation

Front 3

Transverse wave

Back 3

A wave with a direction of propagation that is perpendicular to its direction of oscillation

Front 4

Sonic boom

Back 4

The sound produced as sa result of an object traveling at or above Mach 1.

Front 5

Supersonic boom

Back 5

Any speed that is faster than the speed of sound in the substance of interest.

Front 6

In designing a car's horn, the engineers test the sound of the horn and decide the pitch is too low. To adjust the horn, should the engineers change the electronics so as to produce sound waves with longer or shorter wavelengths?

Back 6

Shorter wavelengths

Front 7

A sound wave is traveling through air with a tempature of 20 degrees Celsius. What is the speed of the sound wave?

Back 7

v = (331.5 + 0.6 X 20)m/sec

v= (331.5 + 12)m/sec

v= 343.5 m/sec

Answer: 343.5 meters per second

Front 8

If the sound wave in problem #3 (speed of 343.5 m/sec) has a wavelength of .7 meteres, what is its frequency?

Back 8

343.5 m/sec [divided by] 500 meters

Meters units are canceled, leaving 1 over a "second" unit.

490.71 Hz

Front 9

A sound wave has a speed of 345 m/sec and a wavelength of 500 meters. What is its frequency?

Back 9

345 m/sec [divided by] 500 meters

Answer: 0.69 Hz

Front 10

If a sound wave has a frequency of 0.69, is it infrasonic, sonic, or ultrasonic?

Back 10

Infrasonic

Front 11

A physicist takes an alarm clock and puts it in an airtight chamber. When the chamber is sealed but still full of air, the physicist is able to hear the alarm despite the fact that he is outside of the chamber. If the physicist then uses a vacuum pump to evacuate essentially all of the air from the chamber, will the physicist still be able to the alarm? Why or why not?

Back 11

No, because there would be no air oscillated by the sound waves to hit his eardrum

Front 12

Are sound waves transverse waves or longitudinal waves?

Back 12

Longitudinal

Front 13

You are watching the lightning from a thunderstorm. You suddenly see a flash of lightning, and 2.7 seconds later you hear the thunder. How far away from you did the lightning strike? (The temerature at the time is 14 degrees Celsius).

Back 13

v = (33.15 + 0.6 X 14)m/sec
v = (331.5 + 8.4)m/sec

v = 339.9 m/sec

Answer: 917.73 meters away

Front 14

Sound waves are traveling through the air and suddenly run into a wall, As the sound waves travel through the wall, do they travel faster, slower, or at the same speed as when they were traveling in the air?

Back 14

Faster

Front 15

In the situation described above, (sound waves hit travel through air and hit a wall, so their speed changes), what happens to the amplitude of the wave? Is the amplitude of the wave smaller, larger, or the same as teh amplitude before the wave hit the wall?

Back 15

Smaller (lower) amplitude

Front 16

A jet aircraft is traveling at Mach 2.1 through air at 1 degree Celsius. What is the jet's speed in m/sec?

Back 16

v = (331.5 + 0.6 X 1)m/sec

v = 332. 1 m/sec( 2.1)

Answer: 697.41 meters per second

Front 17

A jet travels through the air at 596.7 m/sec. If the air has a tempature of 0 degrees Celsius, at what Mach is the jet flying?

Back 17

v = 331.5 m/s

596.7 m/s [divided by] 331.5 m/s = 1.8

Answer: 1.8 Mach

Front 18

Why do jets travel at speeds of Mach 1 or higher only in sparsely-populated regions?

Back 18

The sonic booms produced could damage buildings & people's hearing

Front 19

A guitar player is plucking on a string. If he takes his finger and pinches the string to the neck of the guitar so as to shorten the length of the string, will the pitch of the sound emitted increase, decrease, or stay the same?

Back 19

Increase

Front 20

You hear two musical notes. They both have the same pitch, but the first is softer than the second. If you compared the sound waves of each sound, what aspect(s) of the wave (wavelength, frequency, speed, and amplitude) would be the same? What aspect(s) would be different?

Back 20

Same: wavelength, frequency, speed

Different: amplitude

Front 21

The horn on your neighbor's car is stuck, so it is constantly blaring. You watch your neighbor get into the car and drive away from you, heading towards the nearest place for automobile service. If you listen to the pitch of the horn from the time the neighbor gets into the car until the car goes out of sight, what will happen to the pitch of the horn?

Back 21

It will become lower once the car passes you

Front 22

You are riding your bicycle towards a stationary polic car whose siren is blaring. Will the pitch of the siren sound lower, higher, or the same as it will sound when you actually stop your bicycle? (Assume the actual pitch of the siren stays constant.)

Back 22

Higher

Front 23

You are standing near an interstate highway trying to talk on a pay phone. You have raised your voice because of the noise, so the loudness of your voice is about 80 decibels. The sound of the traffic on the highway is about 100 decibels. How many times larger is the intensity of the traffic's sound waves as compared to those of your voice?

Back 23

80 decibels (0.1 bels) = 8 bels.

100 decibles (0.1 bel) = 10 bels.

Answer: 100 times larger

Front 24

An amplifier can magnify the intensity of sound waves by a factor of 1,000. If a 20 decibel sound is fed into the amplifier, how many decibels will come out?

Back 24

50 decibels

Front 25

If a sound wave has a long wavelenth, it will have a ____ frequency.

Back 25

Low

Front 26

If a sound wave has a long wavelenth and a low frequency, it will have a ____ pitch.

Back 26

Low

Front 27

The usual medium for sound is ___.

Back 27

Air

Front 28

Sound oscillates (parallel, perpendicular) to the direction the wave travels.

Back 28

Parallel

Front 29

A sound wave traveling through 8 degree Celsius air has a wavelenths of 3 meters. What is its frequency?

Back 29

v = (331.5 + 0.6 X 8)m/sec

v = 331.5 + 4.8

v = 336.3 m/sec

336.3 m/sec [divided by] 3 m

Answer: 112.1 Hz

Front 30

Order these mediums from fastest sound speed to slowest sound speed.

Liquid gas solid

Back 30

Solid, liquid, gas

Front 31

A jet travels through 14 degree Celsius air at Mach 4.1. What is its speed in m/sec?

Back 31

v = 331.5 + 0.6 X 14

v = 331.5 + 8.4

v = 339.9 m/sec

339.9 (4.1)

Answer: 1,393.59 meters per second

Front 32

How much more intense is teh sound of thunder (110 decibel) than heavy traffic (80 decibel)?

Back 32

11 bels - 8 bels = 10 X 10 X 10

Answer: 1,000 times more intense

Front 33

You see a lightning flash and 2.3 seconds later you hear the thunder. How far away is the thunderstorm? (The air temperature is 9 degrees Celsius)

Back 33

v = (331.5 + 0.6 X 9) m/sec

v = (331.5 + 5.4) m/sec

v = 336.9 m/sec

distance = 336.9 (2.3)

Answer: 774.87 meters away

Front 34

What is the frequency of a wave that travels at a speed of 5 meters per second and has a wavelength of 1.5 meters?

Back 34

f = 5 m/sec [ divided by] 1.5 m

Answer: 3.33 Hz

Front 35

A wave whose wavelength is 0.15 m travels with a speed of 150 meters per second. What is its frequency?

Back 35

f = 150 m/sec [divided by] 0.15 m

Answer: 1,000 Hz

Front 36

What is the speed of sound in air that has a temperature of 22 degrees Celsius?

Back 36

v = 331.5 + 0.6 X 22

v = 331.5 + 13.2

v = 344.7 m/sec

Answer: 344.7 meters per second

Front 37

You hear the thunder from a lightning flash 2.3 seconds after you see the flash. If the air has a temperature of 11 degrees Celsius, how far away did the lightning strike occur?

Back 37

v = 331.5 + 0.6 X 11

v = 331.5 + 6.6

v = 338.1 m/sec

338.1 (2.3)

distance = 439.53 meters

Answer: 439.53 meters away

Front 38

A longitudinal wave is suddenly stretched so that its wavelength is increased. If the speed of the wave does not change, what will happen to the wave's frequency?

Back 38

Its frequency will decrease

Front 39

Suppose you are wading on a beach that is experiencing waves that move with a speed of 0.5 meters per second and have a wavelength of 0.25 meters. If you stood still, how many waves would hit you every second?

Back 39

f = 0.5 m/sec [divided by] 0.25 m

f = 2 1/sec

f = 2 Hz

Answer: 2 waves per second

Front 40

What is the speed of sound in air when the temperature is 28 degrees Celsius?

Back 40

v = (331.5 + 0.6 X 28) m/sec

v = (331.5 + 16.8) m/sec

v = 348.3 m/sec

Answer: 348.3 meters per second

Front 41

Remember from Module #9 that the outer core of the earth is liquid but the inner core is solid. If a geophysicist is studying how sound waves travel through the core, would he expect the sound waves to travel faster in the inner core or the outer core?

Back 41

Inner core

Front 42

Many flautists also play the piccolo, an instrument that looks like a very small, short flute. Which instrument (the flute or the piccolo) can produce notes with the hightest pitch?

Back 42

Piccolo

Front 43

Are the wavelengths of ultrasonic waves shorter or longer than the wavelengths of sonic waves?

Back 43

Shorter

Front 44

The sound from a typical power saw has a loudness of 110 decibels. How many times larger is the intensity of the sound waves from a power saw as compared to those of normal conversation (40 decibels)?

Back 44

10 X 10 X 10 X 10 X 10 X 10 X 10

10,000,000 times larger