Puzzle in my head

 

I have a puzzle in my head which has turned my world upside down. Maybe you clever people can help me.

The circumference of the Earth at the Equator is 40,000 kilometres. So if you take a piece of string and place it all round the Earth at the Equator it will be 40,000 kilometres long.

Now imagine if, instead of putting the string on the Equator you put it 16 centimetres above the Equator all around the Earth. For example, every few feet you place a stick 16 cms high on the Equator and then place the string on top of it.

It would look like this:

The Earth is the black circle. And the string is the red circle floating 16 cm away above the Equator.

So my question is: How much MORE string do you need? The original length on the Equator was 40,000 kilometres of string. Now you are 16cms away, how much MORE string do you need?

Watch this film and the answer will be revealed:

The answer is that you will only require about ONE METRE of extra string. Just ONE METRE.

Here's how it works. To calculate the circumference of a circle, multiply the diameter of the circle with π (pi). pi (π=3.14).

Imagine a circle 32 cms in diameter, (16 + 16 = 32 cms). 32 multiplied by 3.14 (pi) = 100.48 cms = about 1.5 metres of extra string required.