A few months ago my friends and I went paintballing! It was the first time I went so I didn't know what I was in for. Paintballing encompasses a lot of physics concepts. One example is a projectile. After the paintballs are shot at a high velocity from the gun, the only force acting upon them is gravity. This causes the paintballs to accelerate at negative 9.8 meters per second squared. Because the paintballs are shot at high velocity, it hurts sooo bad when you get hit (especially when you aren't wearing the proper hardcore paintballing gear). Another the physics concept which I happened to perform was the law of inertia: an object at motion stays at motion unless a net force acts upon it. I was running at a constant speed from one big inflatable shield thing to the next not really paying attention to where I was going (because I was watching for any paintballs that might come flying at me) and I ran straight into my friend. She was the net force that caused me (the object in motion) to stop. We both felt pretty stupid after that. Paintballing was a lot of fun but I got some pretty mean battle wounds. (This picture was taken before we got covered in paint, mud, and bruises).

dart guns.

This afternoon my little brother brought some of his friends over and pretty much everything they did had to do with physics: riding bikes, skateboarding, playing basketball and playing with their dart guns. Every time a dart was shot from the gun, it was an example of a projectile. If they held the gun horizantally, the dart would shoot straight out and then drop due to gravity unless it got stuck to the window. If they angled the gun when they shot the dart, the dart would stay in the air longer because it had a higher initial vertical velocity.

waterpolo

This weekend I went to my little brother's intermediate waterpolo game against Le Jardin...which btw our Iolani team won by a lot. Like any other sport that involves balls, waterpolo consists of non-stop projectiles. Whether the ball is being passed to another player or shot to score a goal, when the ball is thrown, it performs a projectile. A projectile anything thrown or shot through the air with only the force of gravity acting upon it. Because gravity is the only force affecting the ball, the waterpolo ball was always accelerating at a rate of negative 9.8 m/s squared (not accounting for air resistance). The motion of a waterpolo ball (a projectile) can be broken down into two motions: horizantal and veritical. Although in terms of the vertical motion the ball is accelerating at a constant rate of negative 9.8 m/s squared, the horizantal dimension has a constant velocity--no acceleration.

Evaluation So Far..

I'd have to agree with a few other students who already posted their journal: physics is so far my favorite science class out of all the ones we've taken. Although it is pretty challenging, I like it because we do a lot of labs and they are all physical and hands on. For me the hardest part as of right now is translating motions to paper to create graphs; this made the test pretty tricky. The homework load is do-able and despite the complaints I had previously made about the on-line text book, I like it because that's one less heavy book I have to carry around. The simulations are also helpful even though they don't always work on my computer. This course is going to be challenging but I'm willing to put the hard work into it. So basically I'm a little nervous about this course but because I am enjoying it so far, I'm hopeful that it will turn out ok.

but

Distance and Displacement

Ever since I got my drivers' license this summer, I have been driving my friends everywhere. Last night my friend and I (we both live in Kaneohe) slept over at our friend's house in Hawaii Kai. This morning after we woke I drove my friend and me back to Kaneohe; however our distance travelled was MUCH greater than our displacement. First of all instead of getting on the freeway and going through town to take the Likelike exit, we went the opposite direction (the less direct route) on the Kalanianiole highway through Waimanalo and Kailua. We knew it was the longer way but we decided it would be worth because of all the scenery. Then once we got into Kailua instead of turning left onto the Pali to take us to Kaneohe, we decided that we wanted Lanikai Juice, so we turned in the opposite (negative) direction to go in to Kailua Town. Once we got our smoothies, we turned around to continue in the positive direction. I passed my house to drop off my friend since she lives past me, finally I turned back around (causing me to go in the negative direction) and drove home. I realized that even though I drove so much, my displacement would have been the same if I just took the shorter, more direct route without making so many detours. I also probably wasted a lot of gas...but it was fun!

This past summer my family and I went to Six Flags in New Jersey. My dad and I rode the Kingda Ka which supposedly is the fastest, tallest roller coaster in the world. While we were waiting in line, there were signs that told us that in the first 3.5 seconds of the ride, we'd accelerate from 0 mph to 128mph. I calculated this to an acceleration of 16.35 m/s squared. The tallest point of this roller coaster is 456 feet and the whole ride lasted less than a minute. I experienced positive acceleration first, then negative acceleration when we were shot vertically into the air (because we slowed down while going in a positive direction) and then negative acceleration again when dropped straight down (speeding up while going in the negative direction). This ride was craziest thing ever and I was speechless/couldn't move afterwards but I'm glad I decided to ride it.