Things you need:
Some eggs
Plastic covering to protect your surface
Empty plastic soda bottle
Duct tape
Box cutter or scissors
Salt, Kosher salt looks the best
Water

The experiment:
Please perform this and all experiments under the supervision and with the assistance of an adult.

This experiment requires cutting the plastic bottle, so please be careful. Cover your hard surface, floor or table, with plastic so you don’t end up with egg everywhere. Try dropping an egg from about 2-3 feet above your hard surface. What happens to the egg?

Cut your plastic soda bottle close to the top, but where it’s wide enough to get the egg in. Now place your egg in the bottle and tape it back up. Drop the bottle with the egg in it from the same height. What happens to the egg?  Open up the plastic bottle, clean it out, and fill it with enough salt water solution so that egg is floating in the bottle. If your egg does not float, you may not have enough salt mixed in. Tape your bottle closed again, and drop the bottle with the egg and salt water from the same height. Now what happens to the egg?

How does it work?
What should happen is in your first two egg drops, the egg cracks. But with the egg in the salt water, the egg doesn’t crack. In the first two drops, the egg goes from moving very quickly, to a complete stop (when it hits the floor) which puts a large amount of force on the small area on the shell that hits the surface. The egg shell is not strong enough to withstand this force, and it breaks.

In the second drop, even when the egg is in the bottle, it still hits the surface on a small area of the egg shell. But when you put the egg in the salt water, the water evenly distributes the force around a large surface of the egg, as the bottle hits the surface. Eggs are made to withstand an evenly distributed pressure and therefore, survive the third drop!

This is one of the reasons a baby inside its mothers tummy is surrounded by amniotic fluid. This makes sure that if there are any impacts to the mother, the fluid helps to distribute the force and keep the baby protected.


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