History Trivia: The Sandwich That Started WWI

Has a bad sandwich ever just kind of thrown your whole day off? Well, have we got a story for you...

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Transcript

00:20

to ship it in a sturdy tube. [Woman holding her trunk warmer]

00:23

The trunk warmer will fit perfectly in a tube with radius three and a height of five.

00:27

You think you have enough cardboard to make the tube yourself, but you're not totally sure... [The tube design drawn]

00:31

How much cardboard do you need?

00:33

Here are your potential answers: A cardboard shipping tube is the shape of a cylinder.

00:38

So to figure out this problem, we'll need to find the Surface Area of a Cylinder.

00:44

Well fortunately, there's a formula for finding the surface area of a cylinder. [The formula is written out]

00:48

But first, let's break down what the cylinder looks like when it's flattened... [Elephant sitting on the cylinder]

00:52

First, we'll need to find the area of each of those circles. [The circles are highlighted with arrows]

00:55

The formula for finding the area of a circle is pi times the radius squared.

01:00

Well our radius we know already is 3, so our formula will be pi times three squared. [The formula with the values inserted]

01:05

Three squared is nine.

01:07

Pi is approximately three-point-one-four,

01:11

so three-point-one-four times nine is twenty-eight-point-two-six. [The working is shown]

01:17

We have two circles, so we'll then need to double that number.

01:21

Twenty-eight-point-two-six times two is fifty-six-point-five-two.

01:27

So far this is easier than knitting that trunk warmer... [Old woman knitting in her rocking chair]

01:30

But we still have to find the area of the middle part of the cylinder...

01:34

… which is a rectangle when rolled flat. [The elephant sits on the cyclinder again]

01:37

To find this area, we'll need to multiply the height, which we know is five, by the

01:40

circumference of the circle. [The circumference of the circle is shown with an arrow]

01:42

This makes up the top and bottom edge of the rectangle.

01:46

We can find out what this is by using the simple formula two pi “r.”

01:50

Two times pi is approximately six-point-two-eight.

01:53

Six-point-two-eight times “r,” which is three in this case, is eighteen-point-eight-four. [The working is shown]

01:59

Now we just multiply that by the height, five, to get the surface area of the middle part

02:03

of the cylinder, which is ninety-four-point-two.

02:06

To get the total surface area, we just add our two numbers together.

02:10

Fifty-six-point-five-two plus ninety-four-point-two equals one-hundred-fifty-point-seven-two. [The total surface area formula is used]

02:18

So the answer is C.

02:19

Sounds like a lot of cardboard.

02:21

Good thing you've bought quite a few nasal hair trimmers over the years. [Pile of nasal hair trimmer boxes]