Diameter

It has a very easy relationship with the radius.

Try to measure a circle.

Where r is the radius of the sphere.

That's a, that's a ninemile radius.

I want to share briefly a tale of two planets. Earth and Venus are exactly the same size.

If you were to put a tape measure to go around it and someone were to ask you what is the diameter of the circle?

Vertical spacing

Circle radius

Vertical Radius

Vertical Radius

dabs per actual radius

Now what is the radius?

We call this distance along the widest point of the circle, the diameter.

We call that word the circumference of the circle.

The lake is three miles across.

Radiotelescope diameter

Or the horizontal radius is going to be 3.

These are just stars.

Apophis is going to hit us.

Our No.4 is Enceladus, one of Saturn's inner moons.

What is the diameter of the circle?

Hellas Basin.

And then you see that the horizontal axis, I guess.

Or the horizontal diameter, is going to be 3.

Now, let's ask another question.

Actually, never!

Regardless of what kind of ID gripping jaws you are using

We will use the adjustable boring ring again to hold the jaws while making this initial bore

But this the current version of it, is a flying airship that is about 35 meters in diameter, about 110 feet in diameter.

I wanted it to convey some proportions that I was interested in, which is the diameter of the Moon and the diameter of the Earth in proportion to each other.

We can multiply both sides of this by the diameter and we could say that the circumference is equal to pi times the diameter.

The pond is 100 meters in diameter.

The hole is two meters across.

Well, that's the same thing as g plus h.

The lake is four miles across.

(Laughter)

You get some sense of the size

And I did one that was about 35 feet long.

Think! Orbit diameter of your planet?

Now, we know how the diameter and the radius relates, but how does the circumference relate to, say, the diameter.

We set the remaining values conservatively based on the insert we're using to cut these steel jaws

Well if this whole thing is your minor axis or maybe you could call your minor diameter if this whole thing is your minor diameter it's called minor, because it's the shortest of all of the diameters of this ellipse.

The hole is about five feet across.

OK, this is a neat property of circles.