Q&A Hero

Q: You can hear sound through an open window from sources that are not in your line of sight because of diffraction.

Q: If the source moves, the wavelength of the sound in front of the direction of motion is smaller than the wavelength behind the direction of motion.

Q: Sound cannot travel through solid steel.

Q: If the source moves away from you faster than the speed of sound in air, you do not hear any frequency but instead a "˜sonic boom."

Q: If the temperature of the air rises, the frequency you hear is higher than f.

Q: If the source moves away from you, and at the same time you run away from the source, the frequency you hear is the same as f.

Q: If you run towards the source, the frequency you hear is lower than f.

Q: NARRBEGIN: Source emits soundA source emits sound at a fixed constant frequency f.NARRENDIf the source moves away from you, the frequency you hear is lower than f.

Q: A wave moves in a rope with a certain wavelength. A second wave is made to move in the same rope with twice the wavelength of the first wave. The frequency of the second wave is half the frequency of the first wave.

Q: You have two identical ropes stretched with the same force between two different sets of posts. The second rope is twice as long as the first rope. The velocity of a wave in the second rope is half the velocity of a wave in the first rope.

Q: You pull on a rope with a certain force, and a wave travels in the rope with a certain velocity. If you double your force, the velocity of a wave in the rope is now times the original velocity.

Q: NARRBEGIN: Force F stretches a ropeWhen a force F stretches a rope of mass per unit length r, the velocity of a wave in the rope is given byNARRENDYou have two ropes of the same length. The mass of the second rope is twice the mass of the first rope. The velocity of a wave in the second rope is times the velocity of a wave in the first rope.

Q: The speed of a wave is the same as the speed of the particles displaced by the wave.

Q: Waves carry energy.

Q: Regions of a longitudinal wave where the particles of the medium are squeezed together are called compressions.

Q: Sound in a vacuum is impossible.

Q: A sound wave in a metal bar is an example of a longitudinal wave.

Q: A water wave is an example of a transverse wave.

Q: When the frequency of the source of a water wave increases, the speed of the waves traveling in the water increases.

Q: When the frequency of the source of a water wave increases, the distance between successive peaks in the wave increases.

Q: The wavelength of a wave divided by the frequency of the wave is the wave's speed.

Q: The maximum displacement of points on a wave from the equilibrium position is the wave's wavelength.

Q: The distance between two successive "˜like" points on a wave is the wave's wavelength.

Q: The number of cycles of a wave passing a point per unit time is the wave's period.

Q: The flash from a camera is an example of a continuous wave.

Q: In the upper atmosphere at altitudes where commercial airlines travel, we find extremely cold temperatures. What is the speed of sound (in metric units) for a temperature of -53.0 oC?

Q: If one lawn mower causes an 80 dB sound level at a nearby point, what sound level at that point would four lawnmowers together cause?

Q: The fourth harmonic of a complex tone has a frequency of 600 Hz. What is the frequency of the tone?

Q: A huge explosion is heard 20 miles away. How long does it take the sound to travel that far? (20 miles = 32,000 meters)

Q: A test tone used on a radio has a frequency of 1,000 Hz. What is the wavelength of this sound in air at normal room temperature? (The speed of sound is 344 meters per second.)

Q: Water ripples are produced by making a cork oscillate up and down at a frequency of 5 Hz. The peaks of the ripples are 0.03 meters apart. What is the speed of the water ripples?

Q: What is the speed of sound in the air inside a furnace where the temperature is 500 degrees Celsius (773 Kelvin)?

Q: Match each item with the correct statement below.a. amplitude i. rayb. constructive interference j. reflectionc. destructive interference k. reverberationd. diffraction l. sound levele. Doppler effect m. transversef. frequency n. ultrasoundg. longitudinal o. waveformh. pitch p. wavelength1/ line used to show the path of a wave2/ occurs when two waves arrive in phase3/ occurs when sound passes through an open window4/ sound waves used to form images of internal organs5/ the maximum displacement of points on a wave6/ the number of cycles of a wave passing a point per unit time7/ measured in decibels8/ the distance between two successive "˜like" points on a wave9/ sound in air is an example of this type of wave10/ affects the frequency of the sound from a moving sound source11/ multiple, random reflection of sound inside a room12/ when two wave are "out of phase" the result is

Q: If the speed of a continuous wave is constant, as you increase the frequency of the wave, the wave must have a proportionally _________ wavelength

Q: As you increase in altitude in the atmosphere, the speed of sound _________.

Q: Combining two sounds of equal intensity will give a sound level __________ higher than the sound level due to just one of them.

Q: A sound level of 80 dB has __________ times the amplitude of a 60 dB sound.

Q: The only way to make sound travel faster in air is to change the air's ____________.

Q: The wavelength of ultrasound at 1 million Hz in air where the speed of sound is 340 m/s is __________.

Q: Two uses of ultrasound are __________ and __________.

Q: In ultrasound the __________ of the sound is much greater than in normal sound.

Q: As you move farther away from a source emitting a pure tone, the __________ of the sound you hear decreases.

Q: When two identical waves undergo _______________ interference, the net amplitude is zero.

Q: Two speakers in a stereo emit identical pure tones. As you move around in front of the speakers, you hear the sound alternating between loud and zero. This occurs because of __________.

Q: You can hear sound through an open window from sources that are not in your line of sight because of __________.

Q: You shout at a cliff, and hear your echo in 2 seconds. If the speed of sound in the air is 340 m/s, the distance of the cliff from you is __________.

Q: Increasing the speed of waves on a guitar string increases the _________ of the sound it produces.

Q: A wave moves in a rope with a certain wavelength. A second wave is made to move in the same rope with twice the wavelength of the first wave. The frequency of the second wave is _________ times the frequency of the first wave.

Q: The wave with the greatest speed is __________.

Q: The waves with the largest frequency are __________ and _________.

Q: The waves with the largest amplitude are _________ and _________.

Q: NARRBEGIN: Snapshot of 4 differentThe figure shows a "˜snapshot" of four different waves in identical ropes stretched with the same force.NARRENDThe waves with the largest wavelength are waves __________ and ___________.

Q: Two examples of a transverse wave are __________ and __________.

Q: Two examples of a longitudinal wave are __________ and __________.

Q: The wavelength of a wave multiplied by the frequency of the wave is the wave's __________.

Q: A _________ wave is one with its oscillations perpendicular to the direction of propagation.

Q: The maximum displacement of points on a wave from the equilibrium position is the wave's __________.

Q: The distance between two successive "˜like" points on a wave is the wave's __________.

Q: A complex tone can be produced by combining two or more __________.

Q: The number of cycles of a wave passing a point per unit time is the wave's __________.

Q: You put one ear on a steel railroad track while your friend a distance of 400 m away taps on the rail with a stone. You will hear the sound through the steel rail in _________ and through the air where the speed of sound is 344 m/s in _______.a. 0.08 s b. 0.5 s c. 1.2 sd. 2.4 s

Q: In order for two waves to interfere completely destructively, they musta. have the same amplitudeb. be exactly out of phasec. one wave's peak must align with the other's valleyd. be transverse wavese. all of the above

Q: The wave with the largest frequency isa. Ib. IIc. IIId. IVe. all of the above

Q: The wave with the largest amplitude isa. Ib. IIc. IIId. IVe. all of the above

Q: NARRBEGIN: Snapshot of 4 differentThe figure shows a "˜snapshot" of four different waves in identical ropes stretched with the same force.NARRENDThe wave with the largest wavelength is wavea. Ib. IIc. IIId. IVe. all of the above

Q: In a plane wave, the wavefronts area. circularb. flatc. paralleld. perpendicular to the direction of propagation

Q: An example of a longitudinal wave is aa. sound wave in airb. wave on a ropec. water waved. sound wave in a metal bare. none of the above

Q: An example of a transverse wave is aa. sound wave in airb. wave on a ropec. water waved. sound wave in a metal bare. none of the above

Q: Sound waves propagate ina. one dimension b. two dimensions c. three dimensionsd. four dimensions

Q: You are on a boat in a fog and know there are cliffs ahead of you somewhere, but you cannot see them. You use your fog horn to send out a blast of sound (assume the temperature of the air is 20 oC) and the time it takes for the sound to return to you is 20.0 s. How far away are the cliffs (in metric units)? Hint: Be careful and think about the physics of the problem. You may want to make a sketch of the situation to help you determine the answer.a. 1798 m b. 3444 m c. 3596 md. 7192 m

Q: You are on an island where a huge explosion at a distance of 500 miles away can be heard. How long (in seconds) does it take the sound to travel to your location? Assume the temperature of the air is 20 oC.a. 1.4 s b. 5.6 s c. 2340.1 sd. 8955.4 s

Q: What frequency of sound traveling in air at 40 oC has a wavelength of 0.50 m?a. 20 Hz b. 344.7 Hz c. 502.9 Hzd. 711.2 Hz

Q: In the upper atmosphere at altitudes where commercial airlines travel, we find extremely cold temperatures. What is the speed of sound (in metric units) for a temperature of -49.0 oC?a. 984.9 m/s b. 300.8 m/s c. 344.7 m/sd. 140.7 m/s

Q: Harmonicsa. are components of a complex waveformb. have frequencies that are integer multiples of the frequency of the complex waveformc. are pure tonesd. have sinusoidal waveformse. all of the above

Q: A sound with ten times the amplitude of another sound is judged to bea. twice as loud b. ten times as loud c. 10 dB higher in sound leveld. 20 dB higher in sound level

Q: If you move twice as far away from a lawn mower running in an open field, the amplitude of the sound you hear will be ___________ what it was before. a. the same as b. twice c. half d. four times e. one fourth

Q: If one lawn mower causes an 80 dB sound level at a point nearby, four lawnmowers together would cause a sound level of ____________ at that point.a. 92 dB b. 84 dB c. 86 dBd. none of the above

Q: Combining two sounds of equal intensity will give a sound level ___________ than the sound level due to just one of them.a. twice as loud b. 3 dB higher c. 10 dB higherd. 2 dB higher

Q: A zero decibel sound levela. has zero amplitude b. is nonsense c. is just at the threshold of hearing.d. none of the above

Q: A sound level of 80 dB has ___________ the amplitude of a 60 dB sound.a. ten times b. twenty times c. one tenthd. twice