Re: Would the small end of an eggshell support more weight than the large end?

That's a wonderful question, Laura. You have probably seen (or done yourself) the demonstration of hands trying to crush an egg. Press end-to-end, the egg won't break easily. Press across the short way, it crushes easily, with predictable yucky results.

Two things contribute to a structure's strength: material and shape. Eggshell is weak in tension and strong in compression. Chicks are not very strong, but by poking with their beaks from the inside, they are able to break the shell. They break the shell in tension.

The trick to making a structure strong with a tension-weak material is to shape the structure so forces create compression and avoid tension. The arch does this.

Picture an elephant sunbathing atop the St. Louis Gateway Arch. The force of the elephant weight is resisted by compression along the steel arch. The ground pushes back and the whole system supports the elephant. This would work even if the arch were made of a tension-weak material like concrete.

Could we make an arch in three dimensions? Sure. Igloos are made of tension- weak ice. Their shape is called a dome. The top of the Capitol building in Washington is a dome. Move the Statue of Freedom off the top and there'd be room for a sunbathing elephant. We could stack sunbathing elephants atop the Capitol to see how much dead weight it could support. (Many people have noted that most of the dead weight the Capitol supports is in the inside.)

But back to your original question: Would the small end of an eggshell support more weight than the large end? The answer is yes. All other things being equal, the "pointier" arch is more efficient than the circular one in creating compressive reaction force. Look at the St. Louis Gateway Arch and its pointy shape. Do you think the designers had sunbathing elephants in mind?

Larry Skarin
Professor, Electrical/Telecommunications Technology
Monroe Community College
Rochester, New York