Eureka!

Following up on Archimedes from the other day (Pi Day), he is probably most famous for a story involving a bath. As the story goes, he was pondering how to measure the volume of an irregular object and he went to take a bath to relax. When he stepped into the full tub, some water spilled out over the edge. He realized that the amount of water displaced by a submerged object (him, in this case) was equal to the volume of the object. He yelled "Eureka!" (I found it!) and ran from the bath to tell others of his discovery, without even pausing to put on some clothes. Whether or not there is any truth to the story, his method is still used today. I've taught introductory labs in which we determine the density of a metal object by weighing it and then seeing how much water it displaces. The mass divided by volume is the density (along the way, this introductory lab teaches students to use the balance and the graduated cylinder). The perhaps apocryphal bathtub story has been recreated in LEGO form by Spiderpudel, Superdave42 and Lord Pappadhum. (Hmm, two of these were built for the Reasonably Clever Mad Scientist Contest. I've featured a couple of those creations here before, but I have to remember to go back and feature others. It's particularly embarrassing that I haven't already done so, since I was one of the judges for that contest.)