Trivia Teaser: Air Resistance

The first person to correctly state the relationship between air resistance and velocity was

A)        Isaac Newton, in 1687
B)        Edme Mariotte, in 1673
C)        Christiaan Huygens, in 1668
D)        Leonardo da Vinci, in 1491

It wasn’t da Vinci this time. (He believed that both aerodynamic lift and drag forces varied directly, that is linearly, with the velocity of an object through the air.) Actually during the centuries after the renaissance, scientific interest in fluid dynamics was driven not by fascination with flight but naval architecture, and the desire to predict hull drag on ships at sea. In Proposition 23 of his Principia, Newton stated that resistance of bodies moving through a fluid is “in a ratio compounded of the squared ration of their velocities, and the squared ratio of their diameters, and the simple ratio of the density of the parts of the system”. But he wasn’t the first. Edme Mariotte was mentioned in a previous Trivia Teaser, so I’ll skip him for now. And actually it was the third one, choice C, that is the most correct. Huygens actually came to the correct conclusion several years earlier. In 1668 he studied the fall of projectiles and following da Vinci and Galileo he initially believed that resistance was directly proportional to velocity. But within a year his experimental data told him otherwise. Huygens was a solitary figure however, and because of his high personal standards was reluctant to publish his findings, and didn’t actually do so until 1690. Huygens in fact accused Mariotte of plagiarism. Yet both were members of the Paris Academy of Sciences, a forum where then as now, members gathered to discuss their findings, theories, and conclusions about the sciences in a collegial atmosphere, so the precise origin of a new idea is often rather uncertain.