Experiment

Treading on eggshells

Carefully break off the small end of four eggs and pour out the insides. Wind a piece of sticky tape around the centre of each eggshell. Cut through the centre of the tape to make four dome-shaped shells (discard the broken end of each shell). Lay the four domes on a table with the cut sides down arranged in the shape of a rectangle. How many telephone books you can lay on top of the shells before they break?

The supportive eggshells

Arches — even those made of eggshells — are strong because they exert horizontal as well as vertical forces to resist the pressure of heavy loads. The crown of an eggshell can support heavy books because the weight is distributed evenly along the structure of the egg.