Bend it like Beckahm

Two summers ago I went on a soccer trip. I played in Pats Cup and Surf Cup. Between those two tournaments, our team went to go watch Galaxy play against DC United. It was a really fun game and we were able to see Beckham play for a little bit. He took a free kick from outside the box and he bent it into the goal. He put so much spin on the ball and it had a mean curve. He applied a torque to the ball, which caused it to rotate. The way he did it is by kicking the side of the ball with enough force to get it to rotate and go forward at the same time. The point of rotation is the center of the ball or the center of mass. The lever arm, the distance from the point of rotation to the point where the force is applied, is the radius of the ball. I always wondered how Beckham got so much rotation in the ball and the answer is in physics. There are three ways to maximize torque. 1)increase the force applied, 2)increase the lever arm distance, and 3)make sure the force is perpendicular to the lever arm. Since the lever arm can't increase, then the two ways Beckham puts so much torque on the ball is having a lot of force and kicking perpendicular to the radius of the ball. It is cool how physics applies to things like soccer and curving a ball.

surfing!

Last weekend, I went to the beach with my cousins JR and Nick. We went to Ali'i beach in the North Shore and we swam and ate huli huli chicken. There was the big surf tournament there but that day it was canceled so we didn't get to watch it. But there were many people out in the water surfing. I thought that there has to be physics involved in this.
From Newton's 1st law we know that things always wants to keep on doing what it's already doing. This means that the wave will want to keep on moving and if a surfer is just sitting on a board, the board will just want to keep on staying still. When you see people surf, they have to paddle in order to catch the wave. This is because they have to match the speed in order to catch it. But for the big waves that are moving very fast, it is impossible for a surfer to match the speed of the wave just by paddling. So lucky for those big wave surfers, there is concervation of energy, which means Potential Energy can be converted into Kinetic Energy. "Dropping in" does just that. A surfer has to paddle (or sometimes, with the big waves, get towed in) in order to gain some speed so the wave doesn't pass right under them. This initial speed halps the board and the surfer to fall down the face of the wave or "drop in". The Potential Energy they had at the top of the wave is now converted into Kinetic energy as they go down it.
( KE top + PE top = KE bottom)

This gives a surfer the speed needed to match the wave's and catch it. There is physics in something as simple and as fun as surfing.

friction is fun!!!

This past Thursday, I was riding home from school with JR and his sister Ashley. It was drizzling so the traffic was bumper to bumper right by Red Hill. So we get past the hill and we are already by the flat part when the person in front of us suddenly stops. JR is paying attention and he stops and one second later, boom! Ashley hits her head on my headrest and JR's knee hits all the buttons so all of the lights on the dashboard comes out. JR's car isn't that bad but the guy's in the back is totaled. He can't even get out of the car and his hood is folded together and bent like a roof. He said that he was going slow and that he tried to break but he skidded.
I realized that there was physics in this excuse. It had to do with friction! This couldn't have been what actually happened because the tires and the road have a certain maximum friction. He said he was going slow but this can't be possible if he slid. The car has to be going a certain speed so that when he stops, the force forward surpasses the friction of the tires and the road. Also he had to have been going fast if he hit us that hard and his car was in that bad shape. There was also another problem with his excuse. He said that he hit his breaks and skidded. But, the car was a more recent model, which means that it should have anti-lock breaks. Even more so, he would have to have been going faster because there is static friction between the tires and the road and not kinetic friction. Static friction has a higher maximum meaning he would have had to be going faster if he didn't have enough time to stop. Either that or he just wasn't paying attention and hit us. It was cool to be able to prove that someone was lying just because of a simple thing like friction.

just like glasses

Physics is very fun and I really enjoy everything we do in class. The concepts relate to real life and things all around me, which makes it easier to understand. It is cool to see how things work and why things happen the way they do sometimes. Just a simple thing like gravity is very important it everyday life. I like the labs a lot because it further explains what we are learning about. I also like the demonstrations like the one where the two ball berrings landed at the same time even though one was launched horizontally and one was just dropped. My anxiety about this class is not being able to understand a certain concept or section and getting totally lost. Other than that I am excited about the other things we will get to do in this class. I think I have been trying hard in this class. I do all my homework and I study for tests and quizzes. I think I need to ask for help more when I don't understand something so that I will be able to get it.
This course is like a pair of glasses for me. Before this, I didn't really realize that many things around me were as facinating as they are. But now things that seemed just ordinary and everyday things are a lot more interesting. There is actually a reason to why a ball moves when I kick it. When I hit someone who is bigger then me, I bounce the other way because of Newton's third law. Glasses make things a lot more clear and helps people to notice what they didn't before. That is how physics is for me. I am able to see what I think is simple and put reasoning behind it and enjoy it more.

distance vs displacement

This weekend my whole family from my dad's side went to Maui. It was my Aunty Renee's birthday so the our parents planned to go and celebrate it on another island. It was really fun because all of my cousins were there and there were four pools with slides, caves, pool-vollyball and pool-basketball. We left on Friday after school and came back on Sunday. I noticed that there was physics in our trip that shows the difference between distance and displacement. Distance just measures the amount traveled. Displacement measures the amount traveled and in what direction. Displacement is the net change in position. The total distance and displacement that our family flew on the plane were different. The distance from Oahu to Maui is around 116.47 miles. So the total distance that we traveled on the airplane was around 232.94 miles, which is to and from Maui. But our displacement was zero. Even though we traveled 116.47 miles in one direction, we traveled that same distance in the opposite direction, making our total displacement zero. Our trip to Maui showed the difference between distance and displacement and how they measue different things.

momentum in pitching

I love watching my cousin play sports. I watch him play football and baseball for Iolani. In this picture Iolani is playing against Damien and JR is pitching. I wondered how pitchers could throw so fast and why they have that big wind up before they throw. I found out that the answer is related to physics. A net force is needed in order to accelerate an object and change its velocity and momentum. A change in momentum is called the impulse. A greater net force that acts on the object or the longer the net force is applied increases the impulse. The pitcher is like the net force that acts on the ball. In pitching, the momentum needs to be transfered from the pitcher to the ball. This causes the ball's velocity and momentum to change. The windup before the pitch is to create more momentum. This gives the ball more momentum and therefore it goes faster. It also helps if the pither is tall. JR is about 6ft which helps him to pitch the ball faster. Taller pitchers can make the ball go faster because they can apply the force for a longer period of time. The big windups that pitchers do before they throw the ball really does matter because it determines the momentum that is going to be transfered and the force that will act on the ball.

physics in soccer

This weekend I played two soccer games. I was kicking around a soccerball afterward to work on some of my skills that I needed to improve on for the next games. I noticed that there was a physics concept in kicking the ball. It is related to Newton's first law. This law states that an object remains at rest or maintains a constant velocity unless a net force acts upon it. Before I kicked the ball, it didn't have any motion. It had a constant velocity of 0m/s. My foot is the exteral net force that acts upon the ball causing it to change its velocity. The ball will not move unless I kick it just like any object will stay at rest unless a net force acts upon it. It also works the other way too. An object that is in motion will stay in motion unless a net force acts upon it. So, the ball will roll at constant velocity (pretending there is no friction) unless my foot touches it . This weekend I realized that there was physics in a game as simple as soccer.