The best way to drop an egg

How shell cracks in the egg drop challenge turned out to be more complicated than scientists thought

- VERONIQUE GREENWOOD

THE EGG DROP challenge is an annual rite of passage for many students learning about physics: Swaddle an egg in cotton balls and masking tape or other materials, and then drop it off the roof of your school. Anyone who has participated in this exercise knows how difficult it is to engineer a structure that will save the egg from a messy end.

Once the eggs are broken, teachers may reveal insights into the physics of impact, including the claim that eggs sitting vertically crack less often than eggs sitting horizontally.

But is that really true?

After running egg drop challenges for university freshmen, Tal Cohen, an engineering professor at the Massachusetts Institute of Technology, began to wonder whether that assertion really fit the picture of a falling egg.

"It's based on the static behavior of an egg," she said. "Dynamic impact is quite different."