Aug 23, 2022
Without further ado, it's time for the new puzzler. I have a plethora of lousy puzzles in front of me, a good plethora of poor puzzles. So I want to just pick one from among them, at random.
This was sent in by somebody whose name I can't read. So I will just claim authorship myself.
A long time ago, we had a puzzle about why manhole covers were round. It's so the cover won't fall through the hole.
That one has nothing to do with this puzzle whatsoever. I just wanted to introduce it because this one is also about manhole covers. Or person hole covers. Whatever you wanna call them.
If you tie a string snugly around the outside of a manhole, one that's two feet in diameter... You have a two-foot diameter manhole cover with a string around it.
And then, you decide that you want the string to have a one-foot space all around the cover. Would you want to lengthen the string? Yeah. You want to lengthen the string so that the space between the person hole cover and the string will be a foot, all the way around.
You would add how much string? You want to add 6.28 feet of string to the original string.
Now, armed with that piece of information, we can now get into the puzzler.
If you take the Earth? What's the diameter of the Earth? 25,000 miles or something like that... You take the Earth and you did the same thing. You put a string all around it.
Now, I untie it and want a one-foot space between the Earth in the string, all the way around.
How much string do you have to add in this instance?
So back to this week's puzzler, about string and manhole covers, and the Earth. Remember, the manhole cover was two feet in diameter. And you need 6.28 feet of string to add one foot is space between the string and the manhole cover.
How much string would you need to add to do this with the Earth? The string is all around the Earth. Miles and miles. How much would you need to add to get one foot of space between the string and the Earth?
And no matter which way you calculate it and what numbers you start with, the answer is the same. It is 6.28 feet! Why? Because it makes no difference. No difference, always adding the same. So no matter how big the circle is, to begin with, or to end with. It always takes 6.28 feet.
It's hard to believe, I know. Some call this the Rope Around the Earth math puzzle. But we tricked ya. We used string!
Isn't that a great puzzler?
