Static Electricity Fun

When my little brother, Ty, was around three or four years old, my older siblings and I liked to rub balloons that we got from parties on his head. It would work really well; we always got hair to connect to the balloon. We knew it was static electricity, but I did not know how it worked. Now I know! So when we rubbed the balloon on his head, we created friction. Electrons from his hair transferred to the balloon, making the balloon negatively charged. From losing electrons, Ty's hair became positively charged. The balloon and his hair were attracted to each other because they wanted to become neutral, so when we pulled the balloon a little away from his head, the hair stuck to the balloon.

The balloon is an insulator, meaning the part that rubbed against his head is the only part of the balloon that was charged. If we had turned the balloon around, the hair would not have stuck to it.

I have another story that is more recent for static electricity. In New York over winter break, the weather was really cold and dry. Arushi and I kept on accidentally shocking each other during the trip. Even if we were wearing all our layers and our coats, we would shock each other. Because objects can keep their charge imbalances longer where there is low humidity, like New York in the winter, we would shock each other as our electrons from our skin or the material transferred everywhere, making everything positively or negatively charged.

Physics in NY

While I was in New York, I noticed many things related to science, like how I could shock other people and vice versa...but I don't know if there's any physics in that, so I choose to write about friction.

I wore boots all the time (because they were warm) but they didn't have a lot of grip on the bottom, so I could slide on smooth tile. Whenever I walked in the hotel lobby where there was tile, there was not a lot of friction between my boot and the floor. It was during the trip when I started to understand why I would not be able to go anywhere controlled if there was no friction. My boot had a harder time gripping the floor and pushing against it to keep moving forward. I had to exert a little more force downward.

I also noticed how great friction is after the zamboni cleaned the ice rink at Central Park. Before they clean the ice, there are a lot of chipped and shaved ice on the rink and the ice itself has marks in it from previous skaters' shoes. It's easier to skate when the ice rink has the marks because they provide friction. After the ice is cleaned, it is smooth. When I stepped onto the clean ice, I almost fell over because my feet were continuing to more without the rest of my body.

The picture is of ice skating.

The Pique Turn

In ballet, we did pique turns across the floor. At the time, I was not thinking torque, but there was certainly a lot of physics at work. So...What keeps a dancer from falling?????

To successfully complete a pique turn, there are certain things that a dancer has to be aware of, such as body placement. We say to bend the knee to push off the ground, pull up, have straight legs, hold the arms up, spot so we know where we're going and to not get dizzy, turn the knee out, hold the head up...
and in physics this would mean...!
In the first step, in order to even get up en pointe and balance, the dancer in the picture has to bend her knee. This provides a force for the dancer to push off the ground. This force is also what helps get the dancer to turn...torque!

By step two, the dancer need to have a center of balance, a center of mass. Everything need to be in line over the box of the shoe (which is the part that the dancer stands on). If the dancer leans to much back, side, or front, then she'll fall because her weight would not be on her center of mass.

During the turn, the dancer can't change any of her body position because that would throw her turn off. If she can hold her placement, she can do multiple turns before landing!

When she lands, she needs to continue to keep everything in line over her center of mass in order to land neatly in a fifth position. By bending her knees, the shock of landing is more easily absorded.

Ultimate Frisbee Fun in Physics

This past week we played Ultimate Frisbee for PE in the Upper Gym. It's a very intense game. It also has a lot of physics in it, but I can't yet identify all of what's going on.

Anyway the first thing is the change in momentum when the frisbee is caught. Once the frisbee is thrown in the air, it has momentum, which is mass multiplied with velocity. The change in momentum is the velocity change times the mass. I don't know the frisbee's original velocity when it's flying in the air, but it goes from that to zero m/s, thus changing the frisbee's momentum. Because the frisbee experienced a change in momentum, it also felt impulse, which is force multiplied with time.

During the game, people sometimes collided with each other. For example, a girl was trying to catch the frisbee and score a point for her team, but then the boy on the other team jumped up in the air and caught it before she could. Then when he came down from his jump, he hit her and she fell down. She was stationary, so when he came down, his momentum is transferred to her because momentum is conserved in collisions.

For another example, I tried to intercept the frisbee from reaching the opposite team, so I ran up behind this one guy and he moved back unexpectantly. I had stopped running at that point, so when he moved back, I fell. He had more momentum than me, so I failed to intercept the frisbee. It was also a bouncy collision because he did not fall with me. If he had, then he would not have caught the frisbee.

Ultimate frisbee is a good game, especially when your team wins. By the way, that rectangle on the side of the picture that's blue and white on the inside is supposed to be the door with the stairs that go down by the I Building.

Ballet Yay!

During one Saturday dance class, we all tried to slide into a right/left split while standing up en pointe. It was difficult because we were not doing it correctly and also that we were afraid of falling.

The teacher (who is also a biochemist, i think) explained to us that we needed to put more weight on our back leg so that we would not be pushing into the ground. She also told us that we needed to slide on the side of the shoe rather than the top of the box (the part of the shoe that you balance on).

We were trying to stand on the pointe and slide at the same time, which is hard because then we were pushing our weight into the shoe in an effort to stay balanced. By putting more force down into the shoe, the floor is pushing back, keeping us from sliding. Also, there is more surface area at the point of the shoe as compared to the side of the box, making more friction between the shoe and the floor.

When we tried putting more of our weight on our back leg and sliding on the side of the shoe on the other leg, our back leg could support us while the front foot slid easily across the floor until we fell into a split.

That was rather confusing to explain in writing...It is much easier to show this sort of thing, so I'm sorry if it does not make sense!

Evaluation

So I currently feel a little lost in physics, but not as badly as I was in chemistry. chemistry was much worse. physics is also more interesting than chem. but anyway, I feel like Alice in Wonderland because she gets lost and she wants to find her way back to the normal world.

I have put effort into this course, but I might have been able to put more into it. or maybe not. I think that I might have killed myself in my other subjects if I had tried even harder in this class. It's a feeling sort of like Alice because she tries to find her way back home, but she gets sidetracked really easily if I remember correctly. Does that have any relation to my situation? Hmmm...

I hope I can get better grades next quarter, but I'll be happy just as long as I get grades above B-. yep. I hope that friction quiz didn't strangle my grade to death because that would be bad.

By the way, everyone should read Through the Looking Glass by Lewis Carroll because its a really great story!

More Physics in Football!

Last night was the football game against St. Louis and Iolani won!!! It was 35 to 30 :D It got really intense at the end with the drums...and everyone was yelling "Go Defense!" yep. Anyway, projectiles.

When the person does the kick off for the other team and the band plays "Back in Black", the ball flies in a projectile motion. In a projectile, there are two motions, a horizontal and a vertical motion. The horizontal velocity stays constant throughout because gravity has no effect on it. On the other hand, the vertical velocity decreases at a rate of -9.8 m/s. At the very peak of the ball's motion, the vertical velocity is zero while the horizontal velocity stays the same. As it flies back to the ground, the vertical velocity increases negatively at a rate of -9.8 m/s.

The vertical displacement would be zero if the ball is kicked off the ground and the other team does not catch the ball. However, if the other team does catch the ball, the vertical displacement is the height of the ball when it is caught. The horizontal displacement is the distance it traveled from where it was kicked to where it was caught.

Yep, the game was super exciting at the end! And all the Raiders looked super happy. Today I talked to a friend on the other team and he said he considered quitting football that night. St. Louis must've been very sad.