
Learning about science can be hard work, but simple machines can make it easier. Let Bill Nye push and pull you around ramps, levers, screws, and pulleys. Simple machines simply make work easier by directing forces over distances. Instead of lifting a heavy box upstairs, you can hook it to some ropes and pulleys and pull it up. Or you can get a ramp and slide it upstairs. Either way, it's less sweat to use the pulleys or the ramp than it is to lift the box straight up by yourself because the force you need is more spread out. Levers, ramps, screws, wheels, wedges, and pulleys are all simple machines designed to direct forces. With simple machines we don't have to push or pull as hard, but we have to push or pull over a longer distance. It's easier to walk up a long set of stairs to the top of the Empire State Building than it would be to climb a ladder to the top, but the set of stairs would be much longer than the ladder. Simple machines are simply scientific.
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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