CHAPTER 20 Flashcards
The pitch of sound is most closely related to _________
frequency
Infrasonic and ultrasonic frequencies are __________.
too low and too high frequencies for human hearing, respectively
What is the relationship between frequency and pitch?
Pitch is the human perception of sound frequency.
What is the average range of a young person’s hearing?
20 to 20,000 hertz
Distinguish between infrasonic and ultrasonic sound waves.
Infrasonic is too low in frequency (below 20 Hz) for humans to hear, whereas ultrasonic is too high (above 20,000 Hz).
Relative to solids and liquids, how does air rank as a conductor of sound?
Relative to solids and liquids, air is a poor conductor of sound.
Sound travels from one place to another mainly in a series of _________.
compressions and rarefactions
The speed of sound in air varies with _________.
air temperature
Why do we frequently see the lightning and later hear the thunder?
Because light travels faster than sound
Distinguish between a compression and a rarefaction.
In a compression, the molecules are closer together than average; in a rarefaction, they are further apart.
Do compressions and rarefactions travel in the same direction, or in opposite directions, in a wave.
They travel in the same direction at the same speed.
A reverberation occurs when sound undergoes
_________.
multiple echoes
An echo is just _________.
the refection of sound
What factors does the speed of sound depend upon?
What are some factors that it does not depend upon?
It depends on temperature and humidity, not on loudness and frequency.
Does sound travel faster in warm air or in cold air? In humid air or dry air?
Faster in warm air, faster in humid air
Which is normally greater, the energy in ordinary sound or the energy in ordinary light? How does the speed of sound compare to the speed of light?
The energy in ordinary light is greater than the
energy in ordinary sound. The speed of sound is a million times less than the speed of light.
What ultimately happens to the energy of sound in the air?
It becomes thermal energy.
When a car veers of the road such that the left front wheel goes of the pavement into the gravel before the right wheel, what will happen to the car, and why?
The car will tend to turn to the left. Because the left wheel hits the gravel frst and slows down before the right wheel, the right
wheel covers a greater distance, causing the car to turn to the left.
What is the relationship between the direction of traveling rays of light and the line representing the wave crests?
The direction of the rays of light is perpendicular to the line representing the wave crests.
What happens to the speed of light waves when they enter water from air?
The speed decreases.
What happens to the wavelength and frequency of the light waves as they enter water from air?
Wavelength decreases, and frequency will stay the same
What is the difference in the speed of sound on a warm day versus on a cold day?
It is faster on a warm day and slower on a cold day.
Why did the campers in Dr. Hewitt’s story hear the sound of the campers across the lake more clearly at night than during the day?
The temperature change from cold at the surface to warm at the top changed
the shape of the sound waves.
How does the direction of sound travel compare to the shapes of the sound waves?
The sound is at right angles to the waves.
