Bogglers
By Scott Kim

Around The World

Suppose Earth is a perfect sphere 25,000 miles in circumference, and you are required to tie a massive loop of string around the equator. Due to a slight miscalculation, your loop of string is 20 feet too long. You start thinking about ways that you can pull the string taut.

1. [Easy] How far off the ground would you need to suspend the string all the way around the equator in order to take up the slack? Hint: The suspended string is a perfect circle, concentric with Earth.

2. [Medium] If you wanted to pull the string taut by placing a pole under the string at one point on the equator, how tall a pole would you need? Hint: You'll need a bit of trigonometry to solve this one.