Powering Up Obama

While I was in New York last May for Economics Challenge nationals, there was a lot of hype over the about-to-be-crowned then nominee Barack Obama. While we were walking around in the city, we noticed that many buildings had electronic newsreels snaking around the ground floor. The pictured reel features an "Angry Obama." Like almost everything in New York City, this reel is powered by electricity. Electricity is created by a flow of electrons carrying electric energy. In order for electricity to power devices, there needs to be circuit connecting the device to a battery or some other electron generator. The circuit should be made of conductive material and must be continuous in order to allow the electrons to travel through the device. (Photo Credit: Leslie Kawano)

The Physics of Tubing

Every summer, I visit my grandmother and her boyfriend in California. They live in a small town in Northern California on a lake. They own a speedboat that they keep on the lake. Whenever I visit them in the summer, I go tubing on their boat. The above picture is from the summer before sophomore year. It is quite fun. When I tube, I lie down on a tube attached by a sixty foot rope to the back of the boat, which zooms around the lake at speeds approaching 45 mph. The rope creates an angle of about 30 degrees above the horizontal. Thus, when the boat pulls the tube, it exerts a force roughly equivalent to cos 30 X mass of me and tube X g. The weight of the tube with me on it was probably equal to 50 kilograms. This means that the boat exerts 424 Newtons of force as it pulls me. When I tube, I try to steer the tube outside of the wake when the boat makes sharp turns. When this happens, I shift my weight such that the tube leans to one side. It then speeds up. This is the equivalent of a car making a banked turn. When the tube leans over, it reduces friction by theta, which allows the tube to move faster.