Name: 回転 (Spinning)
Uploaded: 2021-01-14T10:21:12.000Z
Duration: 17 min 31 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Do you want my head delivered to your door in a box?

様態の副詞

Too bad I only have one head, and I already called dibs on it.

The next best thing is what actually comes in the Curiosity box by V Sauce.

It is chock full of science gear designed by us.

It's pretty amazing, and a portion of all proceeds go to Alzheimer's research.

So a subscription isn't just good for your brain.

Now, if you subscribe right now, there's still time to get this box.

It is full of brain food, including the topic of this video.

If you hold a gyroscope in the palm of your hand upright like this, it will fall over.

You see, the trick is to take the included string and thread it through the hole and then spin the disc around to the string wraps around and around and around and around.

Once it's sufficiently wound up, hold the outside and give the string a firm pole.

Now the gyroscope appears to defy gravity.

The axis and spins around is like glued in place, almost cosmic.

If you could get this to spend long enough, you could actually watch as that access did move.

But not because it actually moved because you and Earth moved around it.

Watch the gyro gyration rotation of the Earth, as Leon Fuko did in 18 52 when the device got its name.

If I give it a good spin and then hang it from its own string sideways, it will remain parallel to the ground.

But process around to get to the bottom of what's up.

Or Wah's ab, as the cool kids are saying nowadays, begin by imagining yourself swinging a ball around your head on a rope.

Even though the ball is following a curved path, its velocity is at any given instant, straight tangent to its path.

You can demonstrate this to yourself by letting go.

The ball will shoot out at the velocity it had at the moment you let go, it doesn't curve away or fly directly away.

While rotating the rope keeps the ball always at the same distance from the center, which means continuously changing the direction of the balls velocity.

And in this case, that force is delivered by tension in the rope.

The same inter molecular forces that attract neighboring rope molecules to each other and are the reason the rope doesn't just disintegrate also resist the ball's momentum, acting on it such that its velocity changes every next instant so as to always follow a circular path.

This center seeking force that acts on the ball is called a centripetal force.

It could be provided by a rope, an entire disc of material, something invisible like gravity or from the other side by a wall or banked track.

Side note noticed that there is no force acting on the ball that goes directly outward away from the center.

What we often hear called a centrifugal or centrifugal force.

You know the force you seem to feel when you lock hands with someone, and you both spin around and you feel pulled straight back or when a car you're in turns quickly, and you're suddenly thrown away from the center.

The thing is, this seemingly outward directed force isn't a force at all.

It's actually Justin objects, inertia, the path the object would take if no other forces acted on it being blocked.

Bio force a centripetal force across sufficiently short time scales and inertial path can seem like it's opposite a centripetal force.

But if allowed to follow its inertial path for a while, the difference becomes more clear.

If the's centripetal forces removed, it will continue along on a path tangent to its previous Circular one.

The outline represents where the ball would be if it hadn't have been released.

Now, at first, the separation between the two appears to occur directly away from the center straight out.

But if allowed to continue, a more interesting path emerges from the perspective of the outline, which is still moving counterclockwise.

The solid ball appears to be receding and dragging behind clockwise.

This is due to the Coriolis effect, which we will talk about soon.

It could really be anything, but I would love to use this ball.

It would be awesome to get these into curiosity boxes down the line.

If I push the ball, it will move in the direction of my force.

But if the ball is moving before I touch it, it's velocity doesn't just disappear.

Instead, both combine and the ball moves according to their some the lower its initial mo mentum, the greater this angle.

Its velocity is as we showed before, at all times, tangent to its circular path.

A centripetal force from gravity continuously swings its velocity around so that every 90 degrees it starts pointing Maur and Mawr in the opposite direction.

A downwards force won't send it straight down.

Instead, the vectors combined, resulting in a new path like this 90 degrees ahead.

It reaches the maximum distance it will travel in the direction of our force before going back.

The key point here is that a downwards force at this location didn't move the orbit like this.

It moved the orbit like this, tilting it 90 degrees ahead of where we acted.

Now imagine the satellite as a small piece of our gyroscope.

Pushing down here will cause the piece to assume a path that would take it like this.

But of course, since the disk is solid and all of its pieces quite rigidly push and pull each other, the gyroscope itself tilts like this.

Or if the gyro pivots around a point below its centre like this, If the gyro wasn't spinning, pushing it down here would have just caused this to happen.

But when something is spinning, its component parts have other vectors you need to consider.

I learned a fun demonstration of this from a great video by Matthias Wandell.

Now I can balance it on the end of a pen just like this.

And if I blow on the side nearest me, it tilts to me.

But if the disk is spinning and I blow in the same place, it tilts to the right.

And if I blow on the site nearest you instead of tilting to you?

If instead of applying my force in one location the whole time, I instead apply the force.

Well, tilt will glide around and around Watch.

But the point is, this is exactly what is going on.

When a gyroscope here on earth is spun up and tilted, the tilt glides around.

What's happening is actually very similar.

Tow my breath, moving around except instead of my breath, its gravity, no matter how perfectly upright a gyroscope is, it will not stay that way forever.

Any deviation, no matter how slight, will allow gravity to form a torque.