1a. define: transverse wave
a wave with a direction of propagation that is perpendicular to its direction of oscillation
1b. define: longitudinal wave
a wave with a direction of propagation that is parallel to its direction of oscillation
1c. define: supersonic speed
any speed that is faster than the speed of sound in the substance of interest
1d. define: sonic boom
the sound produced as a result of an object traveling at or above Mach 1
1e. define: pitch
an indication of how high or low a sound is, which is primarily determined by the frequency of the sound wave
- In designing a car’s horn, the engineers test the sound of the horn and decide that its pich is too low. To adjust the horn, should the engineers change the electronics so as to produce sound waves with longer or shorter wavelengths?
the engineers need to adjust the electronics to emit sound waves with a shorter wavelength
- A sound wave is traveling through the air with a temperature of 30 degrees C. What is the speed of the sound wave?
v=349.5 m/sec
- If the sound wave in problem #3 have a wavelength of 0.5 meters, what is its frequency?
699 Hz
- A soundwave has a speed of 345 m/sec and a wavelength of 500 meters. is this wave infrasonic, sonic, or ultrasonic?
infrasonic wave
- A physicist takes an alarm clock and puts it in an airtight chamber. When the chamber is sealed by 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 the air out of the chamber, will the physicist still able to hear the alarm? Why or why not?
The physicist will not be able to hear the alarm because, without air, the sound waves from the alarm have nothing through which to travel. Thus, they cannot make waves. As a result, there is no sound.
- Are sound waves transverse waves or longitudinal waves?
sounds are longitudinal waves
- You are watching the lightning from a thunderstorm. You suddenly see a flash of lightning, and 2.3 seconds later, you hear the thunder. How far away from you did the lightning strike? (the temperature at the time is 13 degrees Celsius)
780.39 m
- 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?
the sound travels faster in the wall
- In the situation described in #9, what happens to the amplitude of the wave? Is the amplitude of the wave smaller, larger or the same as the amplitude before the wave hit the wall?
the amplitude of the wave will be smaller
- A jet aircraft is traveling at mach 2.5 through air at 1 degree Celsius. What is the jets speed in m/sec?
830.25 m/sec
- A jet travels through air at 464.1 m/sec if the air has a temp of 0 degree Celsius, at what Mach number is the jet flying?
Mach 1.4
- Why do jets travel at speeds of Mach 1 or higher only in sparsely populated regions?
When a jet travels at Mach 1 or higher, it creates a shock wave of air that causes a very loud boom. This boom can damage people’s ears and buildings.
- 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?
the pitch will increase
- You hear two musical notes. They both have the same pitch, but the first is louder than the second. If you compare the sound waves of each sound, what aspect(s) of the wave (wavelength, frequency, speed, and amplitude) would be the same. What would be different?
the wavelength, frequency, and speed will all be the same; the amplitudes of the waves will be different
- 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. Compare the pitch of the horn before he starts to drive away to the pitch you hear as he is drving away from you
the horn’s pitch is lower when it is moving away from you
- You are riding your bicycle toward a stationary police car with a siren blaring away. Will the pitch of the siren sound lower, higher or the same as it will sound when you actually stop your bicycle? (assume pitch stays constant)
higher
- 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 decibel. How many times larger is the intensity of the traffic’s sound waves as compared to those of your voice?
100 times larger than the intensities of sound waves from your voice
- An amplifier can magnify the intensity of sound waves by a factor of 1000. If a 30 decible sound is fed in the amplifier, how many decibels will come out?
60 decibels
