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jcstack6 last won the day on October 1 2016

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About jcstack6

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  1. Sleding

    Many people spend the winter practicing thrilling winter sports such as skiing or snowboarding, but I like to stick with simplicity. Sleding requires very limited skill to still have the thrill of gliding down a hill. There is also a lot of physics behind sleding, specifically how to turn on a sled. People seem to automatically know that they should lean to a side to turn to that side on a sled, but why? It's all about the normal force. The sled glides down the hill because of the force of gravity on the sled and the person in the sled but turning is a different story. Once a person leans to the side they are push by the snow because they have rotated the snows normal force on the sled. Initially the normal force is perpendicular to the sled but once the sled is turned, the normal force is at an angle, causing the sled and the person to be pushed to the side. This is why simply leaning to the slide one wants to turn works in sleding, and the basic concept even holds true in skiing and snowboarding.
  2. Blogmas is my favorite holiday.
  3. That's so cool to think about that energy can't be lost or created even in the scenario of a massive rollercoaster.
  4. Thanks for discussing conservation of angular momentum between the balls as they role, great job.
  5. Returning a serve

    In my limited time playing tennis for school and ping pong in my free time, I've learned how to properly return a fast serve. I would always see a quick serve coming at me and be tempted to swing hard back at it, but that would always end in the ball soaring off to either side. My coach instead told me to just hold my racket still and steady and let the ball bounce off of it. This technique has a lot of physics behind it that makes sense. Think of a ball being bounced on the floor. The floor does not swing at the ball to propel it back to your hand, rather the ball merely hits the still floor and goes back up. This can be thought of an elastic collision where all of the potential and kinetic energy of the ball is conserved causing the ball to bounce back up to one's hand. Similarly in tennis and ping pong, a fast serve met with a still racket causes the ball to go across the net with the same speed as it was served with but in a controlled manner. Therefore, even though swinging at the ball will cause its speed to increase, to get a fast AND controlled return, one should cause and elastic collision with the ball and the racket by holding the racket steady and still.
  6. Basketball

    I often play pickup basketball with my brothers, the teams usually split up as me and Paul vs Nathan and Dave. Paul is garbage, however his terrible form and his "signature move" has a lot of physics involved with it. Paul believes the greatest shot is one where he dribbles along the three point arc and chucks up a shot one handed while falling backward. He believes the best way to make this shot is by aiming for the white square on the backboard. This is surprisingly not the best tactic however. Even though every coach tells their 5 year old players to aim for the magic white box, in Paul case, they shouldn't. Since Paul is moving sideways with some velocity, the ball is also moving sideways with the same velocity. Therefore, if Paul aims for the white box, he will end up missing it because the ball will not travel straight but slightly sideways due to Paul's velocity in the horizontal direction. Therefore, Paul should aim to one side of the white box so that the ball actually hits the white box and has a chance of going in. However, playing with Paul turns into an hour of pain and frustration.
  7. Biking

    Biking is one of the most electrifying activities out there. Picking up speed as you approach a jump, wondering how much air you'll get and then being launched into the air. Not many people, however, know all of the physics behind just simply going off a jump. It can be thought of in terms of kinematics by knowing the bikers initial velocity, but then one neglects how the biker obtained that initial velocity. Rather we can consider work and energy to talk about the correlation between the force of the bike, the distance the biker accelerates, their final velocity and the height they get off of the jump. Since work is equal to the bikes force multiplied by the distance the force is acting for, and since work equals the change in kinetic energy, the greater the force or the greater the distance, the greater the bikers kinetic energy. When looking at kinetic energy of the biker, we can look at linear and rotational, but for simplicity we'll just focus on linear. Since linear kinetic energy is a function of speed and mass, the speed of the biker increases, because the bikers kinetic energy increases and the bikers mass is constant. Finally, if the biker has no potential energy before the ramp, and no kinetic energy at his maximum height, we can set kinetic energy equal to potential energy, a function of height, mass and the acceleration due to gravity. Therefore, the height a biker gets is dependent on the bikers speed, but since his speed is dependent on the bikes force and distance that the force acts, the height the biker ultimately attains is dependent on the bikes force and distance that the force acts.
  8. In a recent lab done in my physics c class, my group was experimentally determining the moment of inertia of six different objects. We set up a ramp for the objects to roll down at an angle of 3.325 degrees. We rolled the objects down the ramp, recorded the time for each object and then found each objects linear acceleration, radius, angular acceleration, mass, net torque and finally moment of inertia. When we checked our answers with our teacher they were horribly wrong, like an average of 200% error. This was because we neglected ed to include for unction in our calculations for torque. This was a major mistake seeing as friction is the only force on the objects that provide a net torque. We went back and fixed our equation for net torque, which previously was the radius of the object multiplied by the x component of the force of gravity, to be the x component of the force of gravity subtracted by linear acceleration and the objects mass, this result was multiplied by the radius to get the net torque. Our lab then produced less massive percent errors, so my advice to you if you are doing a rotational motion lab is don't forget friction!
  9. Cereal

    You may have wondered why it seems that all of your cereal clumps together in the middle of the bowl, even when you only have a few bits left to eat. The fact that cereal accumulates toward the center is due to something scientists have called "The Cheerios Effect." In 2005, the effect was mathematically proven. The surface tension between the milk and the bowl causes the milks surface to cave in slightly toward the middle of the bowl. Similar to the cohesive and adhesive properties of water, these properties in milk cause a concave surface of the milk. Clearly once one understands that the surface of the milk is caved toward the middle of the bowl, it is clear that there is a component of the force of gravity pushing the cheerios together into the middle of the milk's surface as the friction between the milk and the cheerio isn't enough to counteract the component of the force of gravity.
  10. I guess sailing can be cool
  11. That is fascinating that a specific part of your skin can be targeted by using a specific wavelength!
  12. Rising Bread

    My family and I were making bread the other night and my mother had to teach us how a flat piece of dough could turn into a delicious, golden brown loaf. All she knew was that heat made the dough rise, but there is so much more physics involved in making bread rise. In terms of energy, as heat from the oven goes into the dough, the heat energy is turned into mechanical energy in the molecules of the bread, mostly in the form of kinetic energy. This conversion from heat energy to kinetic energy causes the molecules to increase their speed and begin colliding with one another. As the rate of collision's increase, the molecules "look" for more room as to not collide with so many other molecules. This causes the bread to rise as the molecules push outward to avoid hitting other molecules. The conversion of energy combined with molecular movement causes the dense dough to become a fluffy loaf of bread.
  13. Pancakes

    My sister Abby loves to make pancakes for breakfast. She makes three small pancakes at a time using one pan. How does this cook all of the pancakes evenly? This is where physics comes into the equation. The flame is concentrated in the middle of the pan, so wouldn't that be the only place where the pancakes would be able to be cooked? One would assume so, but due to energy and particle movement, the entire pan is able to cook a pancake, even though the flame is not directly under that spot. The flame heats up the molecules in the pan directly above it, causing the heat energy to be converted into kinetic energy. As the molecules then move rapidly, bouncing off one another, the collisions with other molecules in the pan transfer energy from one molecule to another, transferring energy across the whole pan. The kinetic energy in each of the molecules and collisions cause the entire pan to heat up. This is why it is possible to make three pancakes by using just one pan.
  14. I have to get the same surgery pretty soon! Good to know I won't die!