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.

The Physics of Airsoft

Every long weekend, my friends and I like to play Airsoft. Similar to paintball but much cooler, Airsoft is a game in which guys use replicas of assault rifles to shoot bbs at each other in military skirmish games. We play at an Airsoft place at Kaneohe Marine Corps Base. We play in a variety of fields, such as grasslands, forest, and close quarter battle fields. An Airsoft gun is an example of several physics concepts. My gun, and SR 16 M4 Carbine shoots bbs at upwards of 380 feet per second. As the bbs fly, they become a projectile, eventually hitting the ground unless they hit a person or bunker due to gravity. Although the bbs are small and light (0.20 grams), it stings to be shot by one. This is because they are traveling at a high velocity. Some people, like Preston, prefer to use 0.25 gram bbs. Theses bbs go a little slower as they resist the force of the gun more, but they go in a straighter path since they are less susceptible to air resistance. They also hurt more on impact as they weigh 25% more than 0.20 gram bbs. (Photo Credit: Robert Moran)

Center of Human Masses

Last week Friday after school, my friends and I were chilling at our benches in Weinberg. For some reason, Misha, Meatloaf (Jared), Dae (Jon), and me decided to try and see how good we could get at balancing on each other. After a few epic fails, Misha would jump on Meatloaf and I would jump on Misha and none of us would tip over. It was pretty fun. I was pretty surprised that Meatloaf was able to sustain roughly 250 pounds on his back without dying (although, judging by his facial expression in the picture, he came rather close). I then remembered learning about center of mass in physics (actually, I was absent that day). The center of mass of an object is the point at which there is an equal amount of mass on either side such that the object is at equilibrium. Looking at the picture, the center of mass on the x-axis was probably just to the right of Misha's shoulders. If you look down in the picture from that point, it is right near Meatloaf's feet. This means that the equilibrium point was just over a stable point that was supporting all of us. This explains why we did not tip over since the balance point of the three of us was being directly supported by Meatloaf's legs and feet. (Photo credit: Bree Chun)

This picture was taken while I was in New York City for the the Economics Challenge last May. It was taken in a pub-type restaurant in Greenwich Village. It features a game of darts between Braxton Sato and myself. The dart in the outer ring of the bullseye was mine; the dart on the fringe of the board was Braxton's. Unfortunately, we were unable to continue our game. Darts is a game contingent on the laws of physics. When a dart hits the board and pierces it without falling off, the laws of momentum are at work. When the dart strikes the board, it has a momentum equal to its mass multiplied by its velocity. However, when the dart strikes board, the board exerts force on the dart over a period of time. The time multiplied by the average force is called an impulse. The impulse is also the change in momentum. The board exerts a force on the dart, continuously decreasing its momentum, and consequentially, its velocity. This continues until the velocity of the dart is 0. The dart does not bounce off of the board because by the time its forward momentum finally equals 0, it is so far submerged in the board that it is does not bounce off.

Friction: Trick or Treat?

Last Friday, in addition to being homecoming was Halloween. After the game, eating, Ho'olauleia (sp?), and the Burning of the I, my friends and I went trick or treating in Kahala. Outside of the mall, we there was a Longs shopping cart stuck in the mud. Robert climbed into the cart and I tried to pull him out of the grass. We truly are geniuses. However, when I tried pulling the cart wouldn't slide and Robert almost fell out. I was confused. I thought that when I pull an object, the object should move. However, I then remembered friction. Friction occurs when there is a force between two objects preventing them from being slid against one another. The rubber wheels and the dried mud clung together, thus making pulling the cart very difficult. When Robert went in the cart, friction increased. Friction is equal to normal force times the coefficient of friction. Since the coefficient of friction is constant, Robert's 140 pounds increased normal force by approximately 450 Newtons. Thus, our antics were impeded by the phun of friction.

Reflections of the First Quarter of Physics

Physics has been completely different from my expectations of it. I thought that physics would be a really easy course that was conceptual, and not mathematic in nature. I built up these expectations through conversations with former physics students and my own notions about what physics was. To be honest, this was kind of disappointing to me. I have never been a science person, however, I really enjoyed Science 7 and Science 8. I dislike most science classes because they tend to examine physical phenomena in such a mathematical, technical manner that the phenomena themselves become so detached from what we are learning. However, in Science 7 and Science 8, we learned about how things worked, not the formulae that served as mathematical proofs as to why things worked the way that they did. I thought that physics would be focused on learning about the conceptual nature of the laws of physics and how they manifest themselves in the world. Instead, physics seems like basically a harder version of any math course that I have taken at Iolani. Instead of learning why elevators fall in the way that they do, it seems like we just use that example in order to apply mathematical formulae. I don't really understand why we learning that kind of thing. The way I see it, we take math courses every semester at Iolani, so why should physics just be another math course? Except for the lab about getting the ball in the cup, it seems like most of the labs are basically extended math problems in which we must collect the data for the problem, as opposed to just being given it. I wish labs were more like they were in Science 7, Science 8, and even Biology, in which their purpose was to give us hands-on ways of learning and examining the things that we are learning. However, physics has definitely had some very good elements. Unlike most classes, physics can be laid-back and fun. I really like the atmosphere of the classroom, and coming to physics is one of the better parts of my school day. In terms of grades, I am not doing as well as I want to be doing. I am having a hard time incorporating trigonometry (which I haven't taken yet) into the course. I also tend to work sloppily and take more short cuts than is permissible, which seems to be particularly damaging in physics. I think the class might be easier if more time was spent devoted to being taught how to do the problems multiple times.