How can you keep a falling egg from breaking?

By Marshall Brain


http://youtube.com/watch?v=7Wn0KS_eWVc

When you drop an egg onto the counter, it breaks. The video shows that it doesn't break "a little" - it is a catastrophic failure! So the question is: what can we do to keep the egg from breaking?

In the video, we created a cushioning system made of paper towels. We found that it takes a cushion of about 30 paper towels -- a layer approximately two inches thick -- to protect the egg if you drop it from 24 inches above the pad.

What other systems could you create to protect the egg? Here are some experiments you could try at home:

  • A partially inflated plastic bag
  • Foam rubber
  • Styrofoam
  • Bubble wrap
  • Breakfast cereal
  • Water
  • A small trampoline
  • Shoe insoles
  • Etc.
There are all sorts of options. You could compare these options in terms of things like cost, weight, repeatability (does you system work once? 10 times, 100 times?), size, etc.

In your experiments you could also try dropping the egg from different heights: 1 foot, 2 feet, 3 feet, etc. An egg dropped from a higher height has more energy because it is going faster. That means that the cushioning system has to absorb more energy if it is going to protect the egg from breaking.

How fast is the egg going? Here are two equations that you can use to find out:

time = sqrt ( distance / 0.5 * acceleration)

velocity = acceleration * time

[acceleration = 32 feet / second^2]

If the egg is falling from 2 feet, the distance is 2 feet, so the time is .354 seconds. That means that the egg has a velocity of 11.3 feet per second when it hits the counter. If the egg falls from 3 feet, the velocity is 13.9 feet per second, or 23% faster. If you drop it from 8 feet, the speed is 22.6 feet per second. It will take a lot more padding to protect an egg falling that fast.

When you think about how many packages are shipped each year (UPS, for example, handles over 3 billion packages per year) you realize how important padding systems like this can be. If you can create a light, strong, cheap, repeatable system to protect fragile parcels, it could be quite valuable.

Have fun performing your own science experiments!