Do you see that the straight rod can pass through a crooked opening?
That’s because the rod is not upright, but at an angle. If you turn it all the way round, the middle of the rod turns round in a small circle. The ends of the rod turn round in a large circle.
That curved opening through which the rotating rod fits exactly is a special curve. We call it a hyperbola.
Hyperbolas in buildings
Hyperbolas are also found in architecture. Think of the cooling towers of a nuclear power plant or this fancy tower in the Japanese city of Kobe. By using only straight reinforcing bars, you can still give a tower the curved shape of a hyperbola.
Hyperbolas of comets
Comets are cosmic snowballs of ice, gas and grit that move through our solar system. Some comets follow the path of an ellipse (‘a stretched circle’), others that of a hyperbola.
Hyperbolas in chips
The shape of a Pringles chip has its origins in the hyperbola. We call this shape a ‘hyperbolic paraboloid’. Saddles for horses have the same shape.
