HomeArticlesSari on Science: An "eggceptional" physics party trick

Sari on Science: An “eggceptional” physics party trick

Do you think you can drop an egg into a glass of water without touching the egg or breaking it?

Spring is an “eggcellent” time to try this fun physics party trick. If you’re ready to get cracking, here’s the challenge: Do you think you can drop an egg into a glass of water without touching the egg or breaking it? Don’t be chicken — it can be done! I’m not yolking around.

Supplies

  • 1 tall drink glass
  • Water (enough to almost fill the glass)
  • 1 cardboard toilet paper tube
  • 1 metal pie pan
  • 1 egg

Directions

  1. Find a clean, clear workspace — like a kitchen island or dining table — and banish any breakables.
  2. Fill the glass about three-quarters full of water and set the glass on the workspace.
  3. Center the pie pan on top of the glass, rim side up.
  4. Set the toilet paper tube vertically on top of the pie pan, centered over the glass.
  5. Balance an egg on its side on top of the toilet paper tube.
  6. Hold your dominant hand about eight inches from the side of the pie pan, with your palm facing the set-up materials.
  7. Quickly and forcefully smack the edge of the pie pan and pull your hand away. The pie pan will travel, so be sure no one is standing in the way!

What’s happening?

Make your observations first. What happened to the egg?

When you use your hand to apply force to the pan, energy transfers to the pan, making it move. As the pan travels across the rim of the glass, the pan catches the edge of the paper roll, pulling it out from under the egg. There is very little friction between the shell of the egg and the paper roll, so the only force that really acts on the egg is gravity, causing the egg to fall straight down — safely into the glass of water. This is a demonstration of inertia.

What would happen if there was no water in the glass to slow down the egg? Consider what would happen if you used a taller paper tube, such as a paper towel roll. Try it to find out! Or, take the super egg challenge: Try using a cookie sheet or lunch tray instead of a pie pan and place multiple glasses underneath. How many eggs can you get safely into their glasses at once?

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Sari Custer
Sari Custerhttp://azscience.org
Sari Custer is a lifelong science junkie, Chief Science and Curiosity Officer at Arizona Science Center, and mom to daughter Carson (6). Follow her on Twitter and Instagram @SariOnScience and find Arizona Science Center at azscience.org

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