# Rope puzzle

2

#### 2scoops0406

Here's another one but with far less safety implications (I may have lifted this from this forum so apologies if I have)

Assume the earth is a perfect sphere. You have a rope that stretches arounf the equator so the the ends of the rope just touch.

Now you want the same rope to be uniformly suspended 1 foot above the surface, how much extra rope do you need?

#### blondini

That ones as easy as pi

2

#### 2scoops0406

That ones as easy as pi

If your saying it's pi feet, then I'm sorry, that's not correct.

2

#### 2scoops0406

Well sorry about not being intuitive, the point is well made, in that I had to check the calculation a couple of times as I originally thought I'd made a mistake.

#### Softus

Now you want the same rope to be uniformly suspended 1 foot above the surface, how much extra rope do you need?
The answer is (2 * pi) feet.

2

#### 2scoops0406

Now you want the same rope to be uniformly suspended 1 foot above the surface, how much extra rope do you need?
The answer is (2 * pi) feet.

Correct.

#### blondini

I see my enlargement on my pie joke has been removed

2

#### 2scoops0406

I see my enlargement on my pie joke has been removed

My fault, hijacked a post.

#### peteftw

sorry to get in a bit late on this one, are you saying the rope only has to be 6' longer?

#### tim west

what if it's bungee rope?

#### blondini

sorry to get in a bit late on this one, are you saying the rope only has to be 6' longer?

Close. Just two times the value of pi.

(1' extra radius = 2' extra circumference...)

#### peteftw

so what if it was round the circumferance of an elephants belly would it still need to be 6' longer to hover 1'?

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