Have you ever wondered why birds don't break their eggs when they sit on them? What makes the eggs so strong? The secret to egg strength is in its arch shape. Forces applied to the top of the arch are carried along the curve of the arch to the support at each side. A chicken egg can support up to 100 lbs, and an ostrich egg can support up to 1000 lbs.
Arches are found in many man-made structures, including houses and bridges. Arches can be made of wedge shaped blocks called voussoirs. The last block at the very top is call the key stone. We built our own bridges from home-made wooden voussoirs, and tested thier strength by pressing down on the keystone.
Even a paper arch can be strong as long as the base of the arch is anchored to a surface that prevents it from moving horizontally. Our 3-arch paper bridge was strong enough to support a cup full of pebbles!
After building our confidence in the architectural properties of arches, it was time to test if eggs are really that strong. Can we walk on eggs? We took turns walking on 60 raw eggs...
It is easier to walk on eggs with shoes on, since the shoes help to distribute the weight evenly between the eggs. In addition, it is advisable to walk without stomping as if you are, well, walking on eggs :)
In fact the egg shell is so strong that it is nearly impossible to break the egg by pressing the tips of the egg between 2 hands.
Please try this at home and impress your friends and family!