Zipper Around the World

I make zippers for a living. Every few months we produce enough zipper to go around the world, which is 40,075.16 kilometers at the equator. Here is an interesting thought experiment.

One day I’m bored. I haul out 40,075,160 meters of zipper (over 700 tons) from the warehouse, and make a perfect, tight wrap around the equator. With a smile on my face, I inspect my earth-hugging masterpiece. To my dismay, I find that the zipper is on the ground and on the surface of the ocean, getting dirty and wet, which is obviously unacceptable. Being the fickle person I am, I decide to haul in more zipper from the warehouse, and magically raise the entire zipper loop one meter above ground level (and sea level). I call on you, the warehouse manager, to get more zipper to do it.

Here is the question: Based on your intuition, roughly how much more zipper will I need?  How many trucks will you need?


To help out, here is a quick guide:

1%: 400 kilometers (1 big truck)

10%: 4,000 kilometers (four 40′ shipping containers)

100%: 40,000 kilometers (uh, call for quote)


You have 10 seconds to make a guess. Ready?

The answer, surprisingly, is 6.28 meters, or 0.000016%. The additional zipper needed is proportional to the diameter increase (1 meter off the ground = 2 meter diameter increase). Specifically, you will need 2m * pi = 6.28 meters. As the warehouse manager, all you need is to reach in your pocket and pull out some extra zipper, no need for a truck after all.

Leave a Reply

Your email address will not be published. Required fields are marked *