physics

As I was driving home from my tennis match this weekend, a strange phenomenon occurred in my back seat. My water bottle began making a weird noise, and it sounded as if air was trying to escape from it. In a sense, that is kind of what was going on. I thought about why the noise was being made, and it occurred to me that, with the use of my physics knowledge of fluid mechanics, that as I was driving up the mountain, the atmospheric pressure was decreasing. However, the air inside my water bottle was still at the ground level's atmospheric pressure. Therefore, there was a greater pressure inside my water bottle than outside, causing the air from inside to flow out. This can even be expressed in bernoulli's equation. As I go up the mountain, my PE goes up, meaning that air pressure at higher elevations must be lower than air pressure at ground level.

How in the world do boats float?

Going to pearl harbor was a pretty fun experience, though it would have been more fun if it wasn't so hot and muggy. Anyways, the field trip was exciting because we got to ride on a boat and look inside submarines. While I was on the boat, I thought to myself, "Wow, there are a lot of people on this boat. How come this boat doesn't sink?" Then it hit me again. Buoyant force was the answer, something we recently reviewed in our packets. Buoyant force is the force that pushes up on a ship and is equal to the weight of the water displaced. Therefore, as long as the boat displaces enough water to counter the weight of the ship and its passengers, the boat will not sink. Once again, it is amazing how physics is hidden in almost every aspect of our lives, and how it makes our lives more convenient

DRIVING

So I got my permit a few weeks ago and have already gone driving many times. In my few hours on the road I have already experienced many of the dangers that I was taught to avoid. To be a good driver on the highway, one must be able to estimate the acceleration of the car (positive or negative), otherwise an accident could possibly occur. One time while driving on the highway at about 40 mph, I did not judge the speed of the car in front of me well enough, causing my mom to yell "stop! stop!". I quickly hit the brake, but realized that I needed to apply even more stopping power to be sure I would not hit the car. The car came to a sudden stop, and that's when it hit me (no not the car behind me). If i drew acceleration graphs of my car on the highway, or any car, it would basically be a series of intervals that show positive acceleration, negative acceleration, then stopping (when you come to a red light), then a repeat of those intervals. Driving has been tons of fun, and hopefully as I gain more experience I'll become a better driver.

OMG you've got to be joking

Okay so i was browsing the internet searching for a physics blog topic when i came across this video of a korean man shooting an arrow with incredible accuracy. Now i don't know if it was luck or if he is just a really good archer, but it doesn't matter because the video is still awesome. So when looking at the path of the arrow, a lot of physics comes into play. The arrow leaves the bow with a high velocity directed parallel at the ground, but due to gravity, the arrow will start to be pulled towards the earth, the longer it is in flight. The archer has to account for this effect and has to adjust his shot in order to get maximum accuracy. The arrow needs to be perfectly centered in order for it to go inside the tube. Even friction comes into play, between the bow and the arrow, and the tube and the arrow. Pretty much, this video is a good way to waste 3 minutes if you've got nothing better to do besides study for physics.