Too busy to read? Watch on YouTube Why do ducks float? They float because of their center of gravity, their hollow bones, the air in their feathers and air sacs, and the oil on their feathers. Whether or not something floats has to do with the object’s density and the buoyancy of water. Water has […]
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Watch on YouTube How was the meter (metre) defined? In 1791 it was defined as one ten-millionth of the distance from the equator to the North Pole. The word “meter” comes from Greek and means “to measure” or “to count.” That’s why the “meter” in speedometer and altimeter doesn’t mean the unit of distance. The
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Watch on YouTube Why does blood show up under UV light? Because it absorbs all of the light and appears completely black. When we watch crime movies, the police often use a black light to show stains at the murder scene. Well, a black light will make many bodily fluids glow, but it won’t make
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Watch on YouTube How much wind does a wind turbine need? A wind speed of roughly 11 km/h. Wind power has been used for over 2000 years. The windmill was invented in the 7th century in Persia and wind power was harnessed to grind grain. The wind could do the work of a herd of
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Watch on YouTube How does an iron remove wrinkles from clothes? The heat forces the cellulose chains to lie straight. People started wearing clothes about 170,000 years ago. Scientists worked this out by looking at the evolution of lice that live on humans. Lice that live on clothes are different from the lice that live
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Watch on YouTube What makes things sticky? When the molecules in two substances are attracted to each other things become sticky. The stickiness of an adhesive and the stickiness of something like maple syrup are a little bit different from each other. Let’s look at the stickiness of glue, adhesive tape, and maple syrup. There
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Watch on YouTube Why is carbon-based life common? Because carbon can bond with many different elements to allow chemical reactions to happen. On our planet all living things contain carbon. There may be lifeforms on other planets that are made of different elements but on Earth, everything uses carbon in one way or another. Plants,
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How long do black holes last? Black holes will slowly dissolve, but it will take far longer than the length of our universe, so it has never been observed. There are two ways that black holes form. The first way is when a star collapses. As stars die, they burn up all of their hydrogen,
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How does an ion thruster work? It creates thrust by accelerating ions using electricity. An ion is a charged atom or molecule. Atoms always have an equal number of electrons and protons. Electrons have a negative charge and protons have a positive charge. Because there is an equal number of each, the charges balance themselves
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How does a breathalyzer work? The alcohol in a person’s breath reacts with a solution, creating an electrical current. The breathalyzer relies on the fact that when you drink alcohol, some of it gets into your lungs and you breathe it out. That’s why, when you take a late bus home on a Friday night,
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