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!