Why is there no sound on the moon?
A. There is, but astronauts can’t hear the sound through their space helmets
B. Because space is mostly a vacuum, and sound can’t travel through a vacuum
C. Because earth is too far away, and only earthlings make noise
D. Because it’s too cold
The correct answer is B: Because space is mostly a vacuum, and sound can’t travel through a vacuum.
Source: NASA Lunar Science Institute
A technique called ultrasonic cleaning can be used to get rid of:
A. Dandruff (dry skin flakes in hair).
B. Fleas on pets and lice on children’s heads.
C. Common tooth stains such as coffee.
D. Dust, dirt, and other particles on small objects.
The correct answer is D: Dust, dirt, and other particles on small objects.
Ultrasonic cleaning can be used to eliminate dust, dirt, and other particles clinging to small objects such as jewelry. The word “ultrasonic” means that the frequency of the sound waves is too high for a person to hear.
Source: Physics Central (American Physical Society)
Thunder is produced by ________________________.
A. Lightning
B. Cold air
C. Clouds colliding
D. A giant bowling alley in the sky
The correct answer is A: Lightning.
The National Severe Storms Laboratory describes it this way: “Thunder is the sound caused by rapidly expanding gases along a channel of lightning discharge. Energy from lightning heats the air to around 18,000 degrees Fahrenheit. This causes a rapid expansion of the air, creating a sound wave heard as thunder.”
Source: National Oceanic and Atmospheric Administration
When you hold a seashell next to your ear to “hear the ocean,” what are you actually hearing?
A. Vibrations of the air between your ear and the seashell
B. The ocean, of course!
C. Damp air whirling around inside the shell
D. Nothing! You just have an active imagination.
The correct answer is A: Vibrations of the air between your ear and the seashell.
And if you don’t have a seashell handy, just cup your hands around your ear to hear those air vibrations.
Source: Howard Hughes Medical Institute: Ask a Scientist
You have two identical bottles. One is filled halfway with water, and one has just a little water at the bottom. When you blow across the top of each bottle, which bottle makes a lower pitched sound?
A. The bottle with less water
B. The bottle with more water
C. They sound the same
D. Neither makes a sound! This experiment is harder than it looks.
The correct answer is A: The bottle with less water.
Since this bottle contains less water, it has more air in it. When you blow across the top, the air vibrations are slower than in the bottle holding less air. Slower air vibrations lower the pitch of the sound.
Source: National Geographic Kids
Every sound you make is actually a chain reaction of vibrating _____________ colliding (crashing into one another).
A. Molecules
B. Acoustics
C. Electrons
D. Gases
The correct answer is A: Molecules.
Hearing depends on a series of events that change sound waves in the air into electrical signals. Your auditory nerve then carries these signals to your brain through a complex series of steps. Learn more about how we hear by watching this video on our website.
Source: National Public Radio's Science Friday
You can make a phone out of 2 soda cans and a long string. Your phone will work best if the string is ___________.
A. Very loose
B. Slightly loose
C. Pulled tight
D. It doesn’t matter whether the string is tight or loose.
The correct answer is C: Pulled tight.
This blog on the Science Friday website explains how a dad and his son made a homemade phone. They used soda cans instead of paper cups. The writer, Vince Harriman, explains that “the bottom of the soda can turns the sound waves from our voices into mechanical waves. The mechanical waves then travel down the tight string until they reach the bottom of the second soda can, which transforms them back into sound waves... Use a string that doesn't stretch much—the more the string stretches, the more it will dissipate and dampen the 'signal.' Make sure you keep the string taut as you use your 'phone'—any slack will destroy your signal.”
Scientists are using sound waves to study the interior of the sun, which is full of noisy, bubbling, boiling gases. What is the study of the sun's sound waves called?
A. Helioseismology
B. Solar sound science (“triple S”)
C. Sun biology
D. Solcoustics
The correct answer is A: Helioseismology.
That's pronounced: HEEL-ee-o-size-MAHL-oh-gee. The prefix “helio” means sun. Although “seismology” usually refers to the study of earthquakes, there are no earthquakes (or should that be “sunquakes”?) on the sun. In this case “seismology” means the study of acoustic solar waves. Read more about the noisy sun on our website.
As an ambulance approaches you, its siren seems high pitched. After it passes you, the pitch seems lower. What is this phenomenon called?
A. The Miller effect
B. This doesn’t really happen
C. The Doppler effect
D. Sound shifting
The correct answer is C: The Doppler effect.
Watch a video that explains the Doppler effect. This link will open a non-federal website in a new window.
Which one of these surfaces does not reflect sound and amplify noise?
A. Concrete
B. Grass
C. Metal
D. Glass
The correct answer is B: Grass.
Hard surfaces like glass, metal, concrete, and polished wood reflect sound and amplify noise. Some restaurants use these materials to make the place sound lively.
Read more about where you can find loud noises on our Noisy Planet website.
Source: The National Institute on Deafness and Other Communication Disorders
Learn how sounds make their way from the source to your brain.
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