
Listen up, scientists. Bill Nye is here to make some noise in the ""Sound"" episode. Your vocal cords do it. Speakers playing rock music do it. Even a school bell does it. They all vibrate; and that's how sound is made. Plucking a stretched rubber band makes the rubber band vibrate. Air molecules around the rubber band move, pushing other air molecules. As the rubber band continues to vibrate, it sends waves of sound through the air. It's a lot like the ripples you see when you drop a rock into a pond. You hear sound when rippling air pushes on tiny bones in your ears. Nerves in your ears send a message to your brain about the sound you're hearing. Different sounds make different patterns of waves with different distances between them. Plucking, banging, whispering, and yelling are all vibrations in air, yet they all sound very different. Sound vibrations can be thought of as waves moving through molecules. Low-pitched sounds have big gaps between waves, while high-pi
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E11993 · 26m
Things that fly need air. Even though we walk through it, breathe it, and sneeze it, air seems to be a whole bunch of nothing. But air is there, and it's powerful. Balloons inflate because air presses on the insides and outsides of the balloon. Air pressure in tires supports the weight of bikes, buses, trucks, cars, and planes. But air doesn't need to be inside something to exert pressure. Air that moves around pushes, too. What do birds, planes, kites, Frisbees, and helicopters have in common? They fly because moving air creates lift, or a push up. Airplane wings are shaped to push air down. The momentum of the air going down pushes wings up. Air above the wing gets going faster than the air underneath. Fast-moving air zips along, without pushing as hard side to side or up and down. The slow air pushes up from below harder than the fast air pushes down from above ... and you're airborne! Every flying thing, from the tiniest flying insect to the biggest airplane, us
E21993 · 26m
Don't just go with the flow. Settle down on the crust. Imagine a world without any crust. There would be no pies, just goopy filling, no bread, no hamburger buns, and no you or me. That's right. You, and every living thing we know of, live on or in the Earth's crust. And, living things need the Earth's crust to survive. Let's look at the science of the surface. By carefully studying the Earth's surface, scientists have discovered that the Earth is made up of gigantic layers. At the center of the Earth, there is a core – a big ball of solid metal mostly iron. The core is surrounded by a layer of liquid iron and other minerals. We usually just call it the outer core. The next layer, around the outer core is called the mantle. You may have seen a mantle above a fireplace. Well, the mantle is above the Earth's hot core places. The mantle is gooey hot nearly melted rock that flows the way asphalt does on a hot summer day. Scientists often say that the mantle is plastic. It
Breakthrough: The Ideas That Changed the World
2019 · ★ 7.8