Oily Physics

Talk about a Physics packed weekend! I probably saw the most Physics during Family Fair at the game tents, as many of the games relied on projectile motion, especially the Lani Moo, baseball, blast-a-ball, and shoot-the-ring-onto-the-bottle games. However, a knowledge of the workings of momentum and energy are also in order for the plate/octopus dime toss and the floating glass dish + ping pong ball games, as too much energy in the projectile will make it bounce out and you will lose. :-( However, my blog this week is not about Family Fair; it's about the Arizona Memorial. Although I admit that this is perhaps not the best place to be thinking about Phyiscs, I happened to notice that oil was still leaking out of the ship, almost directly below the memorial. However, the first oil that I saw was not rainbow in color; it was white. I first thought that this must be very thin oil, too thin for there to be a phase shift in the two reflecting rays and have constructive interference at any certain color. After seeing a new drop of oil expand into a rainbow of colors and then become this ghostly white sheen on the water, I decided that I was correct. Above I've pictured something like what I saw. However, this oil also led me to another Physic note. Remember the sunglasses from last week? I wore them to Pearl Harbor and Fair. As I was looking at a particularly large area of rainbow, I saw a section in the middle that had no rainbow, appearing as the outside did behind my dark polarized sunglasses. I was curious why this occured and, preparing to try to find out, I picked my head up from a slanted position to strait. But in doing so, I got a better answer than taking off my glasses would have done. As I turned my head, the rainbow disappeared, leaving only the water looking slightly darker than usual, and the ability to see the dark black thick oil floating in the water. I guess the rainbow coming from the thin layer of oil must be polarized, otherwise this would not have worked. I wonder if it is just the light off the oil, or if most light off the water is polarized as road glare is, and that's why polarized sunglasses work so well?