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As teachers begin the new school year, Blick on … is introducing a new occasional feature in which Jacob Clark Blickenstaff answers your questions about the science (or lack of science) in movies, television programs, or even popular literature. In this first installment, the questions have come in from NSTA staff.
In the book Riddle Me This! (a DC Super Friends title), Cyborg rings a carnival strength-tester bell to break several fun house mirrors. I have heard of sound breaking glass before, but I thought the sound had to be high-pitched, not just loud.
That’s a great question. Sound really can break glass, but it isn’t quite as simple as the sound being loud or high-pitched. The key is that the sound waves match the natural resonant frequency of the glass. If you tap the side of a good-quality wineglass, you’ll hear it ring with a clear tone that depends on the size and thickness of the glass. If you want to break a glass using sound, you’ll need to play a tone of the same frequency (or pitch) as the one the glass makes when you tap it. Science teachers doing this demonstration usually use a very powerful marine speaker to break a glass beaker. Watch in this Berkeley Lecture Demo video.
In one episode of the Mythbusters series, the Mythbusters hired a singer and asked him to create the right note with his voice and break a glass that way. Adam Savage discusses that episode in this video. So Cyborg might be lucky enough for the bell to match the natural frequency of one mirror, but there’s no way the single bell could break several mirrors of varying shape and size. Even being off by a tiny amount will prevent the sound from breaking the glass.
Superman uses his freezing breath to put out a fire in Superman Classic: Superman vs. Bizarro (an I Can Read book). Would that work? Why would cold air extinguish a fire better than warm air?
It turns out that a fire needs three things to propagate: fuel, oxygen, and high temperatures. If any one of the three is missing, the fire will go out. Fuel is the material that is burning. In a wood-burning stove, it is the wood. In a gas range, the fuel is the propane or natural gas. When all the wood or gas is gone, the fire will go out. Combustion, or fire, is the combination of the fuel with oxygen, so if no oxygen is present, the fire will die. Many fire extinguishers work by smothering the fire, preventing oxygen from reaching the fuel.
Finally, the materials have to be hot enough for the fire to keep the reaction between the fuel and oxygen going. Wood is exposed to oxygen in the air all the time, but it doesn’t ignite without some help from a match or other hot object. CO2 and water are used in fire extinguishers because they do two things well: They cool the fuel down, and they deprive the fire of oxygen. (When the CO2 leaves the fire extinguisher, it expands and cools to the point that it forms solid crystals of dry ice. It looks like this.) Superman’s freezing breath would still have some oxygen in it, so it wouldn’t be quite as efficient as a fire extinguisher, but the cold could certainly work to extinguish the fire.
In the 2006 film Curious George, George and Ted (better known as the Man With the Yellow Hat) hang from a bunch of helium balloons, and they get pulled along by a kite. Would that work?
The kite-and-balloon aircraft in the film Curious George.
Ah, yes. I must admit to being very familiar with this movie, as my daughter loves it. I have many issues with the balloon scene in this movie. It takes a lot of balloons to hold up a person, and exactly balancing the lift from the balloons with the weight of the person is difficult. Adding George should cause Ted , voiced by Will Ferrell, to sink. But that wasn’t your question.
Your suspicions are right, since the kite is much, much smaller than the bunch of balloons Ted and George hang from. A kite is held up by the wind because it has a large surface area and not much mass. The balloon bunch would actually be a better “kite” than the kite, so the balloons would pull Ted and George along, kite or no kite.
That said, I do like the movie’s message that museums should have at least some interactive exhibits for kids (and adults) to play with and learn from.
Do you have a question for Blick on…? Send it to firstname.lastname@example.org. Blickenstaff will address questions in a future column.
Jacob Clark Blickenstaff is teacher education programs manager for the American Physical Society. He can be reached at email@example.com.
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