yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

What on Earth is spin? - Brian Jones


3m read
·Nov 8, 2024

Translator: Andrea McDonough
Reviewer: Jessica Ruby

The next time you see a news report of a hurricane or a tropical storm showing high winds battering trees and houses, ask yourself, "How did the wind get going so fast?" Amazingly enough, this is a motion that started more than five billion years ago. But, to understand why, we need to understand spin.

In physics, we talk about two types of motion. The first is straight-line motion. You push on something, and it moves forward. The second type, spin, involves an object rotating, or turning on its axis in place. An object in straight-line motion will move forever unless something, like the friction of the ground beneath it, causes it to slow down and stop. The same thing happens when you get something spinning. It will keep on spinning until something stops it.

But the spin can speed up. If an ice skater is gliding across the ice in straight-line motion and she pulls her arms in, she keeps on gliding at the same speed. But if she is spinning on the ice and she pulls her arms in, you know what happens next. She spins faster. This is called the conservation of angular momentum. Mathematically, angular momentum is a product of two numbers, one that gives the spin rate and one that gives the distance of the mass from the axis. If something is freely spinning, as one number gets bigger, the other gets smaller. Arms closer, spin faster. Arms farther, spin slower.

Spin causes other effects, too. If you are riding on a spinning merry-go-round and you toss a ball to a friend, it will appear to follow a curving path. It doesn't actually curve, though. It really goes in a straight line. You were the one who was following a curving path, but from your point of view, the ball appears to curve. We call this the coriolis effect. Oh, and you are riding on a speeding merry-go-round right now at this very moment. We call it the Earth.

The Earth spins on its axis once each day. But why does the Earth spin? Now, that's a story that starts billions of years ago. A cloud of dust and gas that formed the Sun and the Earth and the planets and you and me started to collapse as gravity pulled it all together. Before it started to collapse, this cloud had a very gentle spin. And, as it collapsed, like that ice skater pulling her arms in, the spin got faster and faster. And everything that formed out of the cloud, the Sun and the planets around the Sun and the moons around the planets, all inherited this spin.

And this inherited spin is what gives us night and day. And this day-night cycle is what drives our weather. The Earth is warm on the daytime side, cool on the nighttime side, and it's warmer at the equator than at the poles. The differences in temperature make differences in air pressure, and the differences in air pressure make air move. They make the wind blow.

But, because the Earth spins, the moving air curves to the right in the Northern Hemisphere because of the coriolis effect. If there's a region of low pressure in the atmosphere, air is pushed toward it, like water going down a drain. But the air curves to the right as it goes, and this gives it a spin. With the dramatic low pressure in a storm, the air gets pulled in tighter and tighter, so it gets going faster and faster, and this is how we get the high winds of a hurricane.

So, when you see a spinning storm on a weather report, think about this: The spin ultimately came from the spin of the Earth, and the Earth's spin is a remnant, a fossil relic, of the gentle spin of the cloud of dust and gas that collapsed to make the Earth some five billion years ago. You are watching something, the spin, that is older than dirt, that's older than rocks, that's older than the Earth itself.

More Articles

View All
PURPOSE of WEALTH (Pt3): COMFORT
Hello Alers, and welcome back as we continue our purpose of wealth series. If you haven’t watched the first two parts covering freedom and security, we recommend you start there, as this is the first one to touch on the positive material benefits brought …
Describing numerical relationships with polynomial identities | Algebra 2 | Khan Academy
What we’re going to do in this video is use what we know about polynomials and how to manipulate them and what we’ve talked about of whether two polynomials are equal to each other for all values of the variable that they’re written in. So whether we’re d…
Conditions for valid confidence intervals | Confidence intervals | AP Statistics | Khan Academy
What we’re going to do in this video is dig a little bit deeper into confidence intervals. In other videos, we compute them; we even interpret them. But here we’re going to make sure that we are making the right assumptions so that we can have confidence …
Michael Burry Backs out of Tesla Short
Was come out in the media over the past week that Michael Burry has ditched his short position against Tesla. So, another big name investor has tried to bet against Elon Musk and has run for the exit. However, unlike many others, there’s a good chance Mic…
Drying Fruits and Vegetables | Live Free or Die: How to Homestead
[Music] What I want to do today is show you how I dry my fruit when I have extra. Then I’ll show you some other things that I also like to [Music] dry. So, the thinner you slice the apples, the faster they’re going to dry. If you don’t slice them thin en…
Discover Ancient Wonders on the Coast of Newfoundland and Labrador | National Geographic
[Music] Mistaken Point around us, missed underfoot, petrified. Deep time rises, and Wealth’s to prod our souls here and there, breaking into sudden vow relief. 88% of Earth’s history is called the Precambrian age. Mistaken Point is the only World Heritage…