17.11.07

Physics and the Battle of the Falklands


A classic story from the annals of physics, but is it true?

On December 8, 1914, a British naval squadron was taking on fuel in the Falkland islands. Fresh from their success at the Battle of Coronel just a month before, the German fleet was bearing down on them. Had the British been caught in port, the story would have ended here, with the Germans blocking the exit, and sending every one of Her Majesty's ships to the bottom. However, the Brits had a trick up their sleeve - the HMS Canopus had been intentionally run aground behind a hill. Spotters fed the gunners positions on the German ships, and she opened up with her fore and aft batteries. The suprise attack did superficial damage, but sent the German scouts running back to the main force.

This gave the British enough time to steam out from port and engage the Germans with superior speed and firepower. Once the faster British came within range of the Germans, they opened fire. According to historical documents, it took nearly half an hour to score the first hit.

Why the delay? For years, physics textbooks have cited this battle as an example of the Coriolis force in action. The Coriolis force is a "fictitious force" much like the centrifugal force one feels on a merry-go-round. The Coriolis force has the effect of making projectiles deflect to the right in the Northern hemisphere, and to the left in the Southern hemisphere. The force isn't noticeable for small distances and velocities, but for long-range naval gunnery, it becomes important. The primitive mechanical firing computers of WWI could calculate and correct for the Coriolis force. However, the story goes that the British forgot that in the Southern hemisphere, the opposite correction needs to be made.

Cheers,
Jeremy