ShmoopTube

00:02

Here’s your Shmoop du jour, brought to you by the unicycle.

00:06

They're perfect for the person who has great balance and enjoys getting odd looks from strangers.

00:12

A wheel with a radius of 6 inches makes four rotations.

00:16

How far does a point on the outside of the circle travel?

00:20

Use 3.14 for pi and round to the nearest whole number.

00:24

Got it? Let's get to it.

00:26

To figure this thing out, we need to know the circumference of the wheel.

00:30

To calculate the circumference, we multiply pi by the diameter of the circle.

00:35

Since we know the radius of the circle is 6 inches, we can just double that to get the diameter,

00:40

which in this case, is 12 inches. So to get the circumference, we just need

00:44

to multiply 12 inches by pi.

00:47

So let's do it. Twelve inches multiplied by 3.14, gives the wheel a circumference of 37.68 inches.

00:54

But…we’re not done yet.

00:56

The wheel turns four times, so we need to multiply 37.68 by four,

01:02

which will give us the total distance that the wheel travels in four rotations.

01:07

Some quick calculations…and we've got a distance traveled of 150.72 inches.

01:14

Since we’re rounding to the nearest whole number, the answer is 151 inches.

01:19

And one quick note before we ride our unicycle into the sunset…

01:23

To find the circumference of a circle, we can either multiply the diameter of the circle

01:26

by pi, or we can multiply the radius of the circle by pi and then multiply that by two.

01:33

Since the diameter is equal to twice the radius, the answer is the same.

01:38

Alright, now let's hop on that magnificent one-wheeled contraption and…

01:42

…ride like the wind?

Full Transcript