What is the correct curve for a suspension bridge?
Many people know that the curves called “parabola” and “catenary” have some connection with suspension bridges, but rather than answer the given question, let’s look at things another way.Many people know that the curve of a projectile is a parabola, which is almost right. There are two reasons why the curve is not a parabola. One is that air resistance changes the shape of the curve. The other is that it was never a parabola to start with, even on the airless moon of earth. The curve in a vacuum is an ellipse, with one focus at the centre of the planet, but the part above the ground is so close to the shape of a parabola that the difference is academic for golf balls.In the same way, the curves of the cables of a bridge are close to being parabolas and catenaries, but are subtly different. To gain some insight into the reason, let’s ask other questions.What is the correct curve for the back of a ladybird beetle or coccinelle? What is the correct curve for the sinuous eel? What is the
