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.