1.
A wave with a direction of propagation that is perpendicular to its direction of oscillation is called:
Correct Answer
B. Transverse Wave
Explanation
A wave with a direction of propagation that is perpendicular to its direction of oscillation is called a transverse wave. In a transverse wave, the particles of the medium vibrate up and down or side to side, while the wave itself moves forward in a perpendicular direction. This type of wave is commonly observed in electromagnetic waves, such as light waves, where the electric and magnetic fields oscillate perpendicular to the direction of wave propagation.
2.
A wave with a direction of propagation that is parallel to its direction of oscillation is called:
Correct Answer
C. Longitudinal Wave
Explanation
A wave with a direction of propagation that is parallel to its direction of oscillation is called a longitudinal wave. In a longitudinal wave, the particles of the medium move back and forth in the same direction as the wave is traveling. This type of wave is characterized by compressions and rarefactions, where the particles are pushed together and spread apart, respectively. Sound waves are examples of longitudinal waves, as the air particles vibrate parallel to the direction of the sound wave.
3.
Any speed that is faster than the speed of sound in the substance of interest is called Supersonic Speed.
Correct Answer
A. True
Explanation
Supersonic speed refers to any speed that exceeds the speed of sound in a particular substance. This means that if an object is traveling faster than the speed of sound in air, for example, it is considered to be traveling at supersonic speed. Therefore, the given statement is true as it accurately defines supersonic speed as any speed faster than the speed of sound in the substance of interest.
4.
The sound produced as a result of an object traveling at or above Mach 1 is called:
Correct Answer
A. Sonic Boom
Explanation
When an object travels at or above the speed of sound, it creates a shockwave that produces a loud and distinctive sound known as a sonic boom. This occurs because the object is moving faster than the speed at which sound waves can propagate, causing the waves to pile up and create a sudden change in pressure. The resulting sound is often described as a loud boom or explosion-like noise. Therefore, the correct answer is Sonic Boom.
5.
An indication of how high or low a sound is, which is primarily determined by the frequency of the sound wave, is called:
Correct Answer
C. Pitch
Explanation
Pitch refers to the perceived highness or lowness of a sound. It is primarily determined by the frequency of the sound wave, with higher frequencies corresponding to higher pitches and lower frequencies corresponding to lower pitches. Wavelength, on the other hand, refers to the distance between two corresponding points on a sound wave and is not directly related to pitch. Frequency, as mentioned earlier, is the number of cycles of a sound wave that occur in one second and is directly related to pitch.
6.
A recorder is a woodwind instrument in which the player blows into a tube, setting up a wave in the tube. A musician has 2 recorders. The first one is rather short, and the second one is significantly longer. Which recorder is capable of playing notes with the lowest pitch?
Correct Answer
B. The second recorder (longer one)
Explanation
The longer recorder is capable of playing notes with the lowest pitch because the length of the instrument affects the wavelength of the sound produced. In general, longer instruments produce lower-pitched sounds because the longer wavelength corresponds to a lower frequency. Therefore, the second recorder, being significantly longer, will be able to produce notes with a lower pitch compared to the shorter first recorder.
7.
A popular science fiction movie was advertised with the slogan, "In space, no one can hear you scream." Why is this a true statement?
Correct Answer
B. Because there is little to no air in space for sound waves.
Explanation
This is a true statement because space is a vacuum, meaning it is mostly empty and devoid of air or any other medium that sound waves require to travel. In the absence of air molecules, there is no medium for sound waves to propagate through, resulting in no sound being transmitted. Therefore, even if someone were to scream in space, there would be no air molecules to vibrate and carry the sound waves, making it impossible for anyone to hear the scream.
8.
Do sound waves oscillate parallel to or perpendicular to the direction in which the wave travels?
Correct Answer
A. Parallel
Explanation
Sound waves are longitudinal waves, which means that the particles of the medium vibrate parallel to the direction in which the wave travels. In other words, the oscillations of the sound wave occur in the same direction as the wave propagation. This is why the correct answer is "Parallel."
9.
What is the speed of sound in air that has a temperature of 25 degrees Celcius?
Correct Answer
B. 346.5 m/sec
Explanation
The speed of sound in air is affected by temperature. As the temperature increases, the speed of sound also increases. At a temperature of 25 degrees Celsius, the speed of sound in air is approximately 346.5 m/sec.
10.
A sound wave traveling through 17 degrees Celcius air has a wavelength of 2 meters. What is the frequency of the sound wave?
Correct Answer
A. 170.85 Hz
Explanation
The frequency of a sound wave is determined by the speed of sound in the medium and the wavelength of the wave. In this case, the wavelength is given as 2 meters. The speed of sound in air at 17 degrees Celsius is approximately 343 meters per second. To find the frequency, we can use the formula: frequency = speed of sound / wavelength. Plugging in the values, we get: frequency = 343 m/s / 2 m = 171.5 Hz. Rounding to the nearest hundredth, the frequency is approximately 170.85 Hz.
11.
Which waves have the longest wavelength: sonic waves, infrasonic waves, or ultrasonic waves?
Correct Answer
B. Infrasonic Waves
Explanation
Infrasonic waves have the longest wavelength compared to sonic and ultrasonic waves. Infrasonic waves are sound waves with frequencies below the range of human hearing, typically below 20 Hz. Due to their low frequency, they have a longer wavelength. Sonic waves, on the other hand, are sound waves that fall within the range of human hearing, typically between 20 Hz and 20,000 Hz. Ultrasonic waves have frequencies above the range of human hearing, typically above 20,000 Hz, and therefore have shorter wavelengths compared to infrasonic waves.
12.
During a thunderstorm, the temperature is 10 degrees Celcius. If you see a lightning strike and then hear the thunder 2 seconds later, how far away did the lightning strike?
Correct Answer
D. 675m
Explanation
The speed of sound in air is approximately 343 meters per second. Since we hear the thunder 2 seconds after seeing the lightning strike, it means that the sound traveled for 2 seconds at a speed of 343 meters per second. Therefore, the distance the sound traveled is 2 seconds multiplied by 343 meters per second, which equals 686 meters. However, since we want to know the distance to the lightning strike, we need to divide this distance by 2, resulting in 343 meters. Therefore, the lightning strike was approximately 675 meters away.
13.
A ship 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 water or in the air?
Correct Answer
A. Water
Explanation
Sound waves travel faster in water than in air because water is denser than air. The denser the medium, the faster sound waves can travel through it. Therefore, when sound waves hit the water after traveling through the air, they will continue to travel faster in the water.
14.
A man and woman are singing a duet. The man sings the low notes, and the woman sings the high notes. The woman, since she is singing the melody, is louder than the man. Are the wavelengths of the man's sound waves longer than, shorter than, or the same size as those of the woman?
Correct Answer
A. Longer
Explanation
The wavelength of a sound wave is inversely proportional to its frequency. Since the woman is singing the high notes, her sound waves have a higher frequency and therefore shorter wavelengths. On the other hand, the man is singing the low notes, so his sound waves have a lower frequency and longer wavelengths. Therefore, the wavelengths of the man's sound waves are longer than those of the woman.
15.
A man and woman are singing a duet. The man sings the low notes, and the woman sings the high notes. The woman, since she is singing the melody, is louder than the man. Are the frequencies of the man's sound waves lower or higher than those of the woman?
Correct Answer
A. Lower
Explanation
The man's sound waves have lower frequencies than those of the woman. This is because the man is singing the low notes, which correspond to lower frequencies. The woman, on the other hand, is singing the high notes, which correspond to higher frequencies.
16.
A man and woman are singing a duet. The man sings the low notes, and the woman sings the high notes. The woman, since she is singing the melody, is louder than the man. What about the amplitudes of the waves? Are they larger or smaller?
Correct Answer
B. Smaller
Explanation
Since the woman is singing the high notes, which have a higher frequency, the amplitude of her waves would be smaller compared to the man's waves. This is because higher frequency waves have shorter wavelengths and therefore smaller amplitudes.
17.
A man and woman are singing a duet. The man sings the low notes, and the woman sings the high notes. The woman, since she is singing the melody, is louder than the man. What about the speed of the sound waves? Are they slower, faster or the same as the woman's
Correct Answer
C. The same as
Explanation
The speed of sound waves is the same as the woman's voice. The speed of sound is determined by the medium through which it travels, such as air, and is not affected by the pitch or volume of the sound. Therefore, regardless of whether the woman is singing high or low notes, the speed of the sound waves she produces will remain constant.
18.
A jet travels through 10 degree Celcius air at Mach 3. What is its speed in meters per second?
Correct Answer
B. 1012.5 m/sec
Explanation
The speed of sound in air at 10 degrees Celsius is approximately 343 meters per second. Mach 3 is three times the speed of sound, so the jet is traveling at 3 * 343 = 1029 meters per second. Therefore, the closest option is 1012.5 m/sec.
19.
You are driving in a city that has a siren which sounds for 30 seconds every day at noon. You stop at a stoplight and then hear the sound of the siren. The stoplight then turns green, and you start driving. As you speed up, you notice that the pitch of the siren keeps getting higher. Are you driving toward or away from the siren? (Assume that the true pitch of the siren stays constant.)
Correct Answer
A. Toward
Explanation
When the pitch of a sound increases, it indicates that the source of the sound is approaching the listener. In this scenario, as the person is driving and the pitch of the siren keeps getting higher, it suggests that they are driving towards the siren.
20.
An amplifier takes a 30 decibel sound and turns it into an 80 decibel sound. How many times larger is the intensity of the sound waves coming out of the amplifier as compared to the intensity of the sound waves going into the amplifier?
Correct Answer
B. 100,000 times larger
Explanation
The decibel scale is logarithmic, meaning that a 10 decibel increase represents a tenfold increase in sound intensity. Since the sound is amplified from 30 decibels to 80 decibels, there is a 50 decibel increase, which corresponds to a 10^5 or 100,000 times increase in sound intensity.