Puzzle pageIssue 27
Rabbit and string
A shaggy rabbit story
This is a story about rabbits. It doesn't have to be, it's just that I have a suitable photo and I've been told rabbits make excellent mathematicians (apparently they're very good at multiplying).
Buster is a very large rabbit. One day he is given a ball to play with. This ball happens to be the planet Earth - Buster is, after all, a very large rabbit. He's also given a piece of string which we could, if it didn't confuse matters greatly, call a cosmic string. Being a clever sort of rabbit, Buster decides to wrap the string around the ball and is pleased to discover that it fits neatly round the fattest part of the planet - let's call it the equator for convenience - with a tiny bit left over. This tiny extra bit is exactly 1 metre long.
Now, let's make some assumptions. Let's assume that Buster, being a very large rabbit, is also very cunning and can seamlessly join the two ends of the piece of string to make a large loop. Let's also assume that the planet Earth is not a slightly squashed ball with a bumpy surface but rather a perfectly smooth sphere - this is, after all, how it appears to big Buster.
Now, supposing Buster evens out the gap between the equator and his piece of string (which is, remember, only 1 metre longer than the equator - which is about 40,000 kilometres long), how big will the gap between them be?
Work quickly now or Buster may well have eaten the piece of string before you've finished!