Imagine you would have to put a rope around the moon. Since the moon is 1,738,000 metres in diameter, this is a hard task. Finally you have managed to get the rope around the moon but... it is one meter short.

You decide to dig a groove all around the moon, so that the shorter rope suffices. How deep must this groove be? (Assume the Moon to be a perfect sphere.)

The relationship between radius and circumference is linear, so it makes sense that changing the circumferrence by a constant would affect the radius by a constant as well.

However, if you look at how big a distance the 15 or so centimeters is in comparison with a globe on your desk, and in comparison with something the size of the moon, that disparity may give you some comfort...

Posted by levik on 2002-05-08 20:22:10