Rope Around The Earth Brain Teaser

How much more rope.

Rope around the earth brain teaser.

Band around the earth puzzle. A really simple but still a little non intuitive fact about the circumference of a circle. A math brain teaser. The circumference of the earth is approximately 40 000 kilometers and someone has just made a metal band that circles the earth touching the ground at all locations.

From there it s not hard to believe that adding 3 feet to a rope around the actual earth would raise it almost 6 inches. In fact this brain teaser requires neither an exact measurement of the earth s circumference which in fact varies by many kilometers depending on which circumference you measure nor even an assumption that the earth has a circular cross sect. A fool wants to tie a rope around the earth. The idea is to imagine the earth is a cube or just a square really and ask yourself if you added say 8 feet to the rope how far would that raise it above the square earth.

You come along at night as a practical joke and add just 10 meters to its length one hundredth of one kilometer. From the diagram it s pretty clear it s one foot. If you tie a ribbon around the equator how much longer of a ribbo.