aweld98
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This past Saturday before I got sick, I helped a fellow Physics C student plant a community garden for a service project. While I was laying down rows of tulip bulbs and fertilizer, I got to thinking about plants and how important gravity is to their growth. The roots of plants grow down into the soil in the direction of the gravitational field; plants need soil for nutrients and water, which are key elements for their survival. Without gravity, roots wouldn't have a direction to grow in, nor would they have a force keeping them rooted in the ground. As a result, we would have floated plants that would have no way of acquiring nutrients from the ground, and they would therefore have no way to survive. We all know that without plants there would be no humans, so we sure are lucky to have gravity keeping our plants rooted and healthy.
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Last Wednesday, my tennis team went to individual sectionals. While we ended up losing 7-10, it was not before I ended up badly scraping my knee against the court. See, the opponent hit a great shot, and as I accelerated and bent low to hit the shot, my knee came into contact with the tennis court. The force I was applying due to my sprint was in the direction of where the ball was, yet the frictional force from the court on my knee was in the opposite direction, causing a net force on my knee. This force caused me to miss the ball because it reduced the total net force from my sprint, making my acceleration smaller (application of Newton's second law: F=ma). In addition, because kinetic energy= .5mv^2 and a decrease in my acceleration would have caused a decrease in my velocity, then my total kinetic energy had to have decreased. While some of this lost kinetic energy was restored into potential energy (that I later converted into kinetic energy during the following points), some of this energy must have done work on my knee or transformed into thermal energy when I received that "rug burn" scar.
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I don't play on them a lot, but I hate playing on them because the game seems much more slow paced; probably another application of the force of friction!
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My last blog post was about the impact of rain on the coefficient of friction on a tennis court, and Mr. Baker commented about how different it is to play on clay tennis courts; I totally agree! I rarely play on clay courts, but when I do, it is not at all an enjoyable experience because the ball does not seem to travel as fast. I decided to find out why. Turns out that clay courts have a higher coefficient of friction than the grass at Wimbledon or other regulation courts. Turns out that the clay surface decreases the balls momentum, (p=mv), causing shots that would be quick to be more dull. The reason the momentum decreases is because lose clay clamps around the ball, causing an increase to the already higher force of friction. Because of the conservation of momentum, even the slightest increase to the tennis balls mass (tiny bits of clay) will cause a decrease in the ball's velocity after it hits the ground. This decrease in velocity gives the opponent more time to strike the ball, hence decreasing the effect of a hard, well angled shot. I guess it wasn't just my imagination that points seemed duller and shots didn't seem as hard to hit on clay courts; clay courts really do impact the shots and the time opponents have to hit returns!
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This past week, my tennis team had its final matches before sectionals begin tomorrow. However, due to heavy rainfall, several of our matches were either rescheduled or postponed. Naturally, I thought that there had to be some physics dealing with the impact of rain on the total force of friction when one plays on a court. Turns out that a liquid substance like water decreases the coefficient of friction of the surface it is on (in this case the tennis courts). Because tennis requires a lot of quick stopping and changing of direction, friction is essential for both speed and for staying on one's feet. A decrease in the coefficient of friction would mean that it would take longer to stop and turn than it would on a dry court. Not only that, but a decrease in friction makes stopping, in general, more difficult, which could prove dangerous for players on the court. So, our postponed matches were not in vain; our coaches were trying to protect us from friction, or rather, the lack thereof!
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This year is about to be bomb and I hope you pass your driver's test tomorrow
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This is my first blog for AP Physics C, which I will hopefully update weekly throughout the upcoming school year. Some of my activities outside of school include playing tennis, practicing the violin, and participating in the theater program at school. When I am not participating in any of these activities, I am listening to music or hanging out with friends. I have one younger sister who is now a freshman in high school, and she's pretty cool. I am taking AP-C Physics because I was successful in and really enjoyed Physics B with Mr. Powlin last year. That class was the first science where I really applied math to solve actual problems and began to understand certain mysteries and concepts that govern everyday life, which I found really fascinating. I hope that AP-C Physics can help me expand on what I learned last year and prepare me for the rigor I should expect in college. I definitely want to pursue a career in the science and/or math field, so I hope this class can give me insight to what I might study and experience in the future. I am excited to take this course because I want to be challenged along with my friends; on that same token, I am a bit scared about what is to come in AP-C Physics, but I am sure that, no matter what, it will be a very rewarding year in this course.