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krdavis18 last won the day on November 5 2017

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About krdavis18

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  1. Bend it like Beckham

    As I said in my first blog post, I love playing soccer in my free time, so I thought I would finally explore some of the physics behind a really cool technique in soccer of bending the ball. Players often use this skill when taking free kicks to put a spin on the ball and curve their shot into the goal. This technique is famously used my David Beckham and the video below highlights one of the most famous moments when he used this technique to win a match in the World Cup. It's incredible to see the curved path that the ball takes when you look at the footage of the goal head on. Players like Beckham are able to accomplish this by imparting a spin to the ball. When you kick a soccer ball with the inside of your foot and you hit the ball in its center of gravity, it is going to move off in a straight line. However, if you kick the ball with the front of your foot and kick it slightly off-center and with your ankle bent into an "L" shape, the ball will curve in flight. This is because the applied force on the ball acts as a torque which gives the ball a spin. This spinning in the air then causes the ball to be laterally deflected in flight in what is known as the Magnus effect which causes the "bending" motion of the ball in the air. You can see this represented in the image below: As you can see its pretty neat to learn about the physics behind this cool soccer technique and learn something new about the game!
  2. Here I am again, at the end of the quarter, rushing to finish up blog posts. But that's not to say that nothing has changed. When this quarter first started out, for the first four weeks, I managed to keep up with blog posts and do one over each weekend. However, as time went on and I got further away from my disciplined state of mind, I began to fall back into my old habit of neglecting blog posts. That's not to say that I didn't have some roadblocks along the way that prevented me from doing blog posts like finishing up college applications or preparing for midterms, but I could've done a much better job staying up to date with my blog posts. This upcoming week is not only the start of a new quarter, but also a new semester and a new chance for me to improve upon my time management skills and step further away from procrastination. At the start of this year, my bad habit of procrastination was deeply rooted, so I am not surprised that it hasn't exactly been a breeze to overcome. But I am glad that I have made some progress this quarter and I hope to continue to grow and learn and stay ahead of the game in this next quarter.
  3. Popcorn

    Popcorn is probably my favorite snack ever. But how does a small hard kernel turn into this fluffy, buttery treat? Here is what I learned: Popcorn kernels have a hard shell on the outside, but on the inside there is moisture and starch. Thus when you put a bag of popcorn in the microwave, the kernels inside start to heat up and the moisture within the kernels turns into steam. The steam then tries to escape, but is blocked by the hard outer shell. The pressure that builds up from the steam trying to escape causes the kernel to explode and the delicious white fluffy part that you eat is formed during this reaction. You can learn more about this from this video that I watched: But when the kernel pops, it doesn't just go straight up into the air. It does a sort of somersault when the pressure from the water vapor is released. Scientists captured this amazing reaction of the kernels in slow motion and used physics to help them explain the causes for this type of motion. The initial parts that form act as legs that exert a net torque on the popcorn that causes it to rotate when it pops. You can watch what they found in this video below: Thanks for reading! Now I'm gonna go make some popcorn.
  4. I have recently gotten into the tv series Game of Thrones (which is an amazing show that I would highly recommend) and I have picked up on a couple different aspects that relate to the world of physics. While some elements of the story are clearly impossible in our world, like a 700 foot high wall 300 miles long that is made out of solid ice, it is cool to note some other elements of the show that involve basic physics. For example, you often see catapults which involves the use of torque and rotation to launch projectiles into the air. Another aspect of the show that you can analyze the physics behind is archers, which you see a lot of in the show. When soldiers are told to "loose" an arrow, Newton's third law comes into play in the force applied to the bow string and the force applied to the arrow. You can also analyze the impulse given to the arrow and its motion as a projectile. I hope to explore more of the physics behind Game of Thrones in the future once I finish watching the series.
  5. The Northern Lights

    Wow so fascinating!
  6. Disney Pixar's Up: Exposed

    I love Disney Pixar's movie Up for lots of different reasons, especially for its very imaginative and fun story line. But have you ever wondered how many balloons it would actually take to lift Carl's house? Well if you consider that about 1 liter of helium can lift one gram, then the average balloon that holds 14 liters can lift about 14 grams. So if I wanted to buy enough balloons to lift myself off the ground, that would require about 3,715 balloons. If we suppose that it costs one dollar to fill up each balloon, that's a lot of money. Going back to Up, if you consider the weight of the house and the fact that the house detaches from the foundation, Pixar estimated that you would need 20-30 million balloons to accomplish this. Not only is this an insanely ridiculous amount of balloons, but also an insane amount of money. With 30 million dollars, Carl could've flown to Paradise Falls in a private jet and built a mansion right on the falls. But where's the fun in that right?
  7. Physics in Food

    I wish we did more labs in class that involve food.
  8. The Bizzare Way Butterflies FLy

    Butterflies are so pretty. Cool to learn more about how they fly.
  9. Physics Behind a Fly Fishing Cast

    So cool that you could relate one of your favorite hobbies to physics.
  10. Hacky Sack

    I guess you could make the same argument for juggling a soccer ball. Cool.
  11. Dog Whistles

    I wonder if this could explain why the parents couldn't hear the bell wringing in the Polar Express.
  12. Sonic vs The Average Hedgehog

    I wonder who came up with the idea to make a blue hedgehog that can run that fast.
  13. The Physics Behind Curling

    As I looked into other Olympic winter sports for my third edition of physics in winter, I thought I might explore the physics behind curling a little but more in depth. At first when you consider curling, you automatically think of friction and how that plays a large role in where the stones land during competition. I also thought about conservation of momentum because when the stones knock into one another, it is pretty clear to see that momentum is conserved when one block moving with some initial speed immediately stops after hitting another stone that was initially at rest. However, there is an entire other layer of physics behind the sport of curling when you consider the rotation that is involved. I found this video that goes into depth about the unique movement of the stones in curling when they start to spin on the ice. I like the idea that its not always the most athletic team that wins in sports but sometimes its the physical manipulation of objects that allows more intelligent teams to win. This goes well with the information I've collected in other blog posts about how the physics behind sports can help athletes perform on a higher level. As he said, it's true that countries like Sweden that have scientists researching the physics of curling most often have Olympic athletes on the podium for curling. Whoever said that brains can't beat brawn in an athletic competition clearly never took a physics class.
  14. The Physics Behind Skiing

    In this second addition of physics in winter, I will explore the physics behind skiing. Three popular skiing events that physics plays a large role in include alpine or downhill skiing, Nordic or cross country skiing, and ski jumping. Each sport can be manipulated using physics to achieve faster speeds and greater results. In alpine skiing, there are several elements of physics that come into play. On a most basic level, downhill skiing involves the conversion of potential energy at the top of the hill into kinetic energy as the skier approaches the bottom of the hill. But as the skier goes around sharp turns through gates during a race, the physics becomes much more complicated. You can dive deep into the complexity of a perfect curved turn and the physics behind it, but here's a short video that helps explain it. Another major factor in downhill skiing is air resistance. You often see skiers in this crouching position, as shown in the picture below, to help them go faster. By crouching down low, skiers are reducing their projected frontal area, thus reducing the amount of drag force on them. This technique is also used in ski jumping as a skier descends the hill and attempts to gain the most kinetic energy at the bottom of the hill so that they will land the farthest away from the hill. Another strategy they use to increase their distance is employed during takeoff. Skiers minimize drag and maximize lift when they lean forward and make a V-shape with their skis, as shown in the picture below. By spreading the skis into a V-shape instead of leaving them parallel, the skier increases the projected frontal area of the skis that is perpendicular to the direction of air flow relative to the skier. This increases the lift force that allows the skier to stay in the air longer and reach farther distances. This technique was initially ridiculed when it was first introduced by Swedish jumper Jan Bokloev in 1985. However, the physics behind the V-shape prevailed and by 1992, all Olympic medalists were using this style. Finally, in Nordic skiing, a skier must push himself forward using his own force, rather than being able to rely on the force of gravity to gain speed. To do this, they use a strategy vary similar to what skaters do which I discussed in my last blog post. Here is a picture to help you get a better idea of what I am referring to. Thanks for reading! nordic skiing.webp
  15. The Physics Behind Skating

    At this time of year, when the weather gets colder and the ground is covered with snow and ice, there are many activities that people take part in that physics plays a crucial role in. These festivities include skiing, sledding, and skating as well as even simpler things like driving on icy roads and cutting down your Christmas tree. So in spirit of the holidays, I thought I would explore the physics behind some of these activities in a series of winter blog posts. In my first post, I will be exploring the physics behind skating. Figure skating, ice hockey, and even just leisure skating are fun to watch and participate in because of the low level of friction between the ice and the blades of skates that allows one to go so fast. With such little friction, in order to start moving forward, a skater must apply a force perpendicular to the blade of the skate. You can see this concept demonstrated in the image below. While watching a hockey game the other day, someone asked how the players are able to skate backwards. This seems to come very easily to those who play hockey or figure skate regularly. But for the rest of us, we can use physics to help us understand how to skate backwards. It is actually quite similar to skating forwards, but instead of turning your skate outward, you turn it inward. However, a skaters blades usually never leave the ice when they are skating backwards and they instead glide in a type of "S" pattern. It is pretty cool to see someone skate backwards at fast speeds because it is harder to push off against the ice Another part of skating that we talk a lot about in physics has to do with figure skaters spinning. When a figure skater enters a spin, they start off slow with their arms outstretched, but as they bring their arms in tight they are able to increase their speed. If you look at the equation for angular momentum, L = Iw it can help you make sense of this change. When they pull their arms in close to their body, they are essentially decreasing their radius and thus reducing their moment of inertia. Then, due to the law of conservation of momentum, their rotational velocity increases. Here is a short old video that demonstrates this. https://youtu.be/l2VuosSk9zU Speed skaters also take advantage of physics to increase their speed in numerous ways. They reduce their air resistance by crouching which decreases their frontal area and allows them to accelerate and maintain a greater speed. Speed skaters also take advantage of slip streams, which I talked about in more depth in one of my recent blog posts. Many different elements pertaining to physics can be manipulated to create faster, more efficient athletes in the world of skating. With the winter Olympics approaching, it will be interesting to see what new things the athletes can accomplish and examine the physics behind it. But its also pretty amusing to examine what happens when non-professional athletes put on skates. Thanks for reading and enjoy this video!

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