I was playing Mariokart DoubleDash this weekend, and I realized that it has a lot to do with centripetal force. It may not be real centripetal force since it is just a videogame, but anyways...Centripetal force is important when making turns. I noticed that I had to apply the brakes a lot to make it around some bends (see the sparks in the picture?). In this case, friction was the centripetal force. My cart would spin out when there wasn't enough friction. The centripetal force was also always directed inward. Mariokart DoubleDash even involves bouncy collisions because you get to throw shells and firebombs at other players. The mushrooms also make you accelerate :)

So, me and my brother were playing darts this week and it made me think of physics. The dartboard was at rest when the dart collided with it. I guess that made it a completely inelastic collision since they "stuck" to each other. That means that although momentum was conserved, there was still a change in kinetic energy. Since our darts really suck (they're the cheap kind with plastic tips; our mom didn't want the wall to be destroyed), sometimes a bouncy collision occurred. The dartboard didn't move because it was nailed to the wall, but the dart rebounded off the wall in the opposite direction. I'm not really sure if this was an inelastic or elastic collision, but I do know that momentum was still conserved.

I was playing foozeball with my brother this weekend and we were having an all out war that involved all five balls. Each individual ball had its own momentum once it was struck by one of our "men" or after it rebounded off one of the walls or other balls. The collisions reminded me of those problems we did in class because once they hit each other, the balls would bounce off each other at different angles. Thanks to Mr. Kohara, I now know that the y-components of each balls's momentum are the same regardless of their different angles. I think all the collisions I witnessed were elastic collisions since foozeballs are kind of like billiard balls. Anyways, my brother completely killed me...I really suck at blocking shots, especially when I have to keep track of five different balls!

Halloween was a lot of fun, even though me and my cousins did have to walk a lot farther to get our usual amount of candy. I swear, some houses turned off their lights as soon as they saw (or heard) us coming. We walked up soooo many hills. I realized we each did work because we had to carry our candy bags up each hill. Since the force and displacement vectors were in the same direction, we all did work. Even though we sort of walked in a zigzag path because we were visiting houses, at the top of each hill, we still would have done the same amount of work if we had walked straight up each hill. In the picture, those of us on the stairs also have a greater amount of potential energy than Chad, Justine, Jodie, and Rayn who are the bottom and have zero potential energy.

Ist Quarter Eval.

Yay! The first quarter is (almost) over! Physics has gotten a lot better...I don't feel so overwhelmed anymore. I had a lot of fun doing the bullseye labs, even though me and Ryan missed every single one! Class was also very entertaining when Mr. Kohara, um, ate it when he was pushing the stool :) Making the projectile movie was also cool because it made me think about the physics in every day life. I thought the first few chapters, with velocity and acceleration graphs, were the hardest. The graphs just really confused me. I did like the last chapter on Newton's Laws though, because it was the one that made the most sense. I think I'm actually getting a little better at doing physics problems and drawing graphs. I hope I continue to improve in the 2nd Quarter! Anyway, overall, the first quarter was really fun :)

Crabbing involves tension and force. I went crabbing in Oregon last summer, and it was really fun! First, you drop your net basket off the side of the boat and let it sink to the bottom. After a period of time, you haul on the net basket rope to bring it back up. Because you pull at an angle, the force has both a vertical and horizontal vector. Tension is also involved because the rope must be kept taut, otherwise the crabs will be able to fall out of the basket. Since the rope touches the side of the boat as you haul up the crabs, there is friction involved too. I had to apply a lot of force to haul up my basket...I never knew crabs could be so heavy :)

My cousin, Sugar, thought it would be fun to hang onto Uncle Chris's foot and have him drag her around. This is an example of friction. Each time my uncle took a step, his force forward had to overcome the static friction between Sugar and the ground in order for him (or Sugar) to move anywhere. When he succeeded in dragging her, that meant he overcame the maximum static friction. Because Sugar is pretty light, it took less force for my uncle to overcome the maximum static friction than it would have if she was twenty pounds heavier. As Sugar was dragged across the ground, kinetic friction was involved since she was no longer at rest.