If a balloon was filled by a vacuum -- rather than helium or air -- would it float? Check out this HowStuffWorks podcast to learn the science behind balloons and vacuum.

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An MRE -- or meal ready to eat -- contains precooked, sterilized food originally made to nourish soldiers. Check out this HowStuffWorks podcast to learn more about the retort packaging that makes MREs possible.

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Also known as 'lie detectors,' polygraphs are used to record an individual's vital signs, such as breathing rate, pulse, and so forth. Check out this podcast from HowStuffWorks to learn more about polygraphs and the art of lie detection.

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A Boeing 747 uses approximately one galloon of fuel per second -- over the course of a ten hour flight, it might burn 36,00 galloons of fuel. How does this compare to a car? Check out this HowStuffWorks podcast to learn more about airplane mileage.

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CDs store music using 44,100 16-bit digital samples per second, adding up to about 10 megabytes per minute -- and that's too large to move easily move across the internet. Check out this HowStuffWorks podcast to learn how MP3 files solve this problem.

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All cells contains thousands of enzymes, and each of these enzymes is necessary for the cell. Check out this HowStuffWorks podcast to learn which enzymes cause apples and potatoes to turn brown upon exposure to oxygen.

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In houses with a built-in sprinkler system, anti-siphon valves prevent pesticides, pet waste, and other contaminants from polluting the home's water source. Check out this HowStuffWorks podcast to learn more about anti-siphon valves.

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A normal 120 volt outlet in the US has two vertical slots and a role hole centered below the slots -- the outlets with a pair of red and black 'test' and 'reset' buttons are known as GCFI outlets. Check out this HowStuffWorks podcast to learn more.

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By using a computer to monitor the rotation of the car's wheels, an anti-lock braking system helps drivers avoid skids. Could this computer also monitor flat tires? Check out this HowStuffWorks podcast to learn more about brake systems.

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The sound of gunfire is incredibly loud, and it is amazing that anything is able to silence a firearm. However, the principle behind a gun silencer is surprisingly simple. Check out our HowStuffWorks article to learn more about silencers.

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