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goalkeeper0

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  1. goalkeeper0
    In class today, while doing the preliminary questions to the lab, we debated whether a clay or rubber ball, of equal mass, would push a door closed more. At first, I thought that the clay would close the door more; but, since the masses are equal, I rethought my intial response. The question is basically asking which medium will create the greatest impulse. Because the clay sticks to the door, the collision is inelastic, and energy is lost as the clay sticks to the door. Because the rubber ball bounces off the door, the collision is elastic. Kinetic energy is conserved for elastic collisions, and the change in velcoity is greater (impulse=m(change in velocity)). So, the impulse is greater with the rubber ball.

    [ATTACH=CONFIG]508[/ATTACH]I found this picture online which helps to explain the elastic collsion in this problem.
  2. goalkeeper0

    Goalkeeping Physics

    By goalkeeper0,

    Physics separates the good from the great goalkeepers.

    1. The Understanding of Momentum- A goalkeeper must keep his weight shifted forward, standing on the balls of his feet. When a shot comes, the goalkeeper will try to save the ball while moving forward. Therefore, due to conservation of momentum, any rebounds will deflect away from the goal. A flat-footed goalkeeper (weight on heels) will deflect shots backward, into the goal.

    2. The Analysis of Vectors- While preparing for a shot, a goalkeeper must analyze vectors at all times to determine where he should stand. Given that a forward from the opposing team has the ball on the end line of the field, it is improbable that he will shoot the ball, because he has no angle. So, in this situation, the goalkeeper should stand a step or two off his line, toward the back of the goal, to prepare for a cross.

    3. The Maximization of Impulse- The best goalkeepers purchase the most expensive goalie gloves. Why? One reason is that they can afford them. But, also, the most expensive goalie gloves are made of the softest foam, with premium cushioning in the palms. This foam "absorbs" the shot for a greater period of time (maximizing impulse); so, less rebounds are given up. Cheaper gloves are made of tough foam which decreases impulse, making it harder to hold on to the ball.

    4. The Knowledge of Torque- On breakaways, when the opposing forward is dribbling to the goal uncontested, it is up to the goalkeeper to make a save. A great goalkeeper will strip the ball from the forward's feet, and send the player flying. How is this done? The goalkeeper slides out on the grass, attacking the ball low. Since torque is greatest when applied further from the point of rotation, the low force at which the goalkeeper hits the attacker with causes the attacker to spin and fly into the air. Yeah torque!
  3. goalkeeper0

    Fork trick

    By goalkeeper0,

    While I was dutifully studying physics today, because we are in our independent unit, I remembered the experiment Mr. Powlin did last year with the forks and toothpick. This experiment shows the concept of center of mass quite nicely. First of all, center of mass is the point on a system that moves as if all the mass of the system were concentrated at that point, and all external forces acted only on that point. In the magical experiment Mr. Powlin did last year, he shoved two forks together, so that they were connected between the tines. Then, a toothpick was wiggled between the forks. The toothpick was then balanced on a drinking glass, and the forks seemed to hover. The end of the toothpick between the rim of the glass, and the center of the glass, was burned. And, the toothpick ended up just barely balancing on the rim of the glass. Meanwhile, the forks were still attached to the toothpick. Why don't the forks fall? The center of mass of the toothpick and fork system is right below where the toothpick rests on the rim. Therefore, the system is in equilibrium. So, in the end, physics can explain this magical trick.

  4. goalkeeper0
    This weekend, my brother was flipping through the TV channels, and a very interesting sport came on. The Dutch sport of Fierljeppen, similar to pole vaulting, involves a person sprinting, jumping onto a long pole at an angle, climbing to the top of the pole while it tilts over, and hopefully landing on sand on the other side of a pond. This sport is also known as canal jumping, as the athlete clears a body of water. In terms of the energy of Fierljeppen, here it goes. A person of mass, m1, and velocity, v1, applies a force to an angled pole of mass m2, and an initial velocity of zero. When the athlete grabs onto the pole, the kinetic energy of the athlete is converted to potential and kinetic energy of the system (athlete and pole become a system of mass (m1+m2) until the athlete releases the pole, and lands in the sand). As the person climbs up the pole, the kinetic energy decreases, and potential energy increases to the 90 degree point. It's basically free fall from that point. Hopefully the sand is deep, and the pole doesn't break!

    Click on this link to watch this peculiar sport.


  5. goalkeeper0
    As advised by Mr. Fullerton, I did the Coat-hanger bubbles experiment to further understand flux!

    Pre-experiment preparation:
    First, in my closet I found a nice metal coat-hanger suitable for the trial. After attempting to reshape the coat-hanger, I learned that my hangers are very strong, or that I lack strength; so, I went to my brother's toolbox and grabbed pliers to help bend the wire into a slinky-like shape. My coil ended up having four turns. I then ventured into my kitchen to fill the sink with soapy water. With the bubbly solution complete, I was ready to start the experiment.

    The experiment:
    I dipped my wire coil into the water, and slowly pulled it out. I found that the bubbles didn't form well to the structure. So, I compressed the coil by pushing the turns closer together. When I tried again with the compressed coil, the bubbles formed nicely between each turn and along the outside of the coil. The formation of the bubbles between each turn demonstrated how the number of turns matter when calculating flux. Therefore, the more turns, the greater the flux. Hence, the equation for magnetic flux is:





    N=number of turns



    A=area within one loop



    B=magnetic field



    =angle between magnetic field and positive normal direction


    Everyone should try this experiment before the test on Wednesday!
  6. goalkeeper0

    Relative Age

    By goalkeeper0,

    As graduating seniors, we are getting old. No more high school, it's off to college! But, just how old are we? On the earth we are about 18 years old, give or take a few months. Because the other planets are different distances from the sun, they have different periods of revolution. Therefore, in relation to many planets we are very young (Neptune) or very old (Mercury).

    A planet's period is given by:

    = distance from planet's aphelion to sun
    = distance from planet's perihelion to sun

    Periods of planets (in Earth years):
    Mercury: 0.241
    Venus: 0.615
    Earth: 1
    Mars: 1.881
    Jupiter: 11.86
    Saturn: 29.46
    Uranus: 84.32
    Neptune: 164.8

    Age of 18 year-old earthling on planets:
    Mercury: 74
    Venus: 29
    Earth: 18
    Mars: 9
    Jupiter: 1
    Saturn: 0.6
    Uranus: 0.2
    Neptune: 0.1

    As period increases, one's relative age on that planet decreases.
    So, as seniors, we may be walking the stage soon; but on Mars, we would only be half-way there!
  7. goalkeeper0
    Even though we launched our bottle rockets a few weeks ago, I thought I would reflect upon team Brazanah's rocket performance.

    With prior knowledge in the field of building bottle rockets, team Brazanah was determined to succeed in the bottle rocket competition this year. We mainly focused on constructing a well-made parachute. We knew that especially on a windy day, a parachute can greatly slow down the rocket during its fall. Just as we put parachutes on rockets for the Kerbal Space Program to salvage parts and save Kerbals, we put a parachute on our bottle rocket. As a result, the drag force (F=-bv), resisting the pull of gravity as the rocket plunged downward, was greater for our rocket than for others. Parachutes seem simple, but to have them actually deploy is another story. Luckily, with guidance from another group, we learned the proper parachute folding technique. We also weighted the nose cone to make sure it fell off as the rocket hit its peak and flipped. The rocket's descent definitely was longer than its climb, primarily due to our successful parachute.

    We did not have time to add fins to the rocket; however, if we did, the rocket would have been more stable on the way up. This is because the fins would counteract the sideways motion of the rocket as water escapes. Fins are similar to adding a SAS on a Kerbal Space Program rocket . Even without the fins, our rocket seemed to climb pretty straight. All in all, for Physics C team Brazanah finished on top with a time of 5.85 seconds in the air. Go Brazanah!
  8. goalkeeper0
    In early September, in the very beginning of my time in AP Physics C, I was hesitant about the workload and difficulty of the course. When Mr. Fullerton introduced integrals to us for the first time, I knew from then on that the class would be no piece of cake. The funny thing looking back is that I enjoyed the calculus parts of physics by the end of the year very much. With a solid calculus background, the "hard math" aspect of the AP did not seem so hard. For me, the hardest part of the class was reading the problems and deciding in which direction to think. I had trouble reading the questions and immediately knowing which equation to use first, which equation to use second, and so on. I tried helping myself by reading the textbook and taking notes, along with making flashcards for the equations. By the time the AP rolled around, I was nervous, but felt prepared to do well. After taking the AP, I am happy to say that Mr. Fullerton prepared us very well as he made our tests harder than the AP itself. All in all, I look forward to the physics I take in college. I hope that from the AP tests I get some college credit; but if I do not, I know that I will at least have the background necessary to succeed in physics mechanics and electricity/magnetism. I wish the best to all of my AP Physics C classmates and the future students of AP Physics C! Go Physics!
  9. goalkeeper0

    Donuts

    By goalkeeper0,

    Happy (belated) National Donut Day! This American day of celebration for sugary breakfast rings occurred yesterday on June 7. Yesterday, people from across the nation stopped by Dunkin Donuts to receive a free donut. These consumers devoured the sticky treats without thinking about the history or science behind the donut. But, the history and science, particularly physics, is interesting. So, I will now discuss the connection between donuts and physics.

    The Dutch brought the idea of deep-fried balls of dough over to the western hemisphere. Originally, the dough balls were spherical, solid, and small. Over time, as American confidence grew, potion sizes also increased. Donut makers tried making bigger and bigger donuts to attract more customers. The physics of heating, and heating efficiently then came into play. The large donuts burnt on the outside and remain uncooked in the middle. The dough wads did not heat evenly. Producers couldn't match the demand for larger donuts, because they couldn't prepare larger donuts. One man by the name of Captain Hanson Gregory then changed donut history. Captain Gregory made a circular cutter and removed an inner circle from the dough. And, the ring shape of donuts today was created!

    The modern donut with an extracted center exists solely because one man thought about physics. Captain Gregory knew about thermodynamics and heating. He knew that for Americans to eat larger donuts, larger donuts needed to become more spread out. By increasing surface area, the donut heats and cooks faster and more evenly. To all of those donut lovers out there, thank Captain Gregory for the design of the classic ring donut.
  10. goalkeeper0
    The Law of Conservation of Energy: Energy may neither be created nor destroyed.

    One of the most simple transformations of energy occurs when a ball is dropped from height, h. Before being released, the ball possesses potential energy equal to mgh with m=mass, g=gravitational constant, h=height. While the ball is in motion, before it reaches the ground, its kinetic energy= (1/2)mv2 increases and potential energy decreases. When the ball hits the ground, some energy is converted to friction. So, when the ball rebounds off the floor, it will not exceed the height it was released from.

    Well, Disney broke this fundamental law in their 1997 film, Flubber, which was a remake of the 1961 film, The Absent-Minded Professor. In Flubber starring Robin Williams, Flubber-- aka green flying rubber, bounces to the sky when dropped from 4ft off the ground. Obviously, Disney threw the law of conservation of energy out the window to create this funny fictitious substance. Flubber, when applied to the soles of the shortest, whitest, weakest, worst basketball players, allowed the athletes to jump remarkably high. The best part in the film comes right before the buzzer of the basketball game when a player with Flubber on his shoes jumps from mid-court to do about eight somersaults in the air and fly head down through the basketball hoop with the ball for the win. Best buzzer-beater ever.

    I'd like to see this happen in a March Madness game. But, for now and probably forever, physics restricts both the idea and creation of Flubber.
    [ATTACH=CONFIG]622[/ATTACH]
  11. goalkeeper0

    Gothic Cathedrals

    By goalkeeper0,

    Obvious connections between Physics and Calculus, or Physics and Chemistry exist. However, what about Physics and Humanities? Recently, in Humanities class, we continued our Middle Ages unit with a lesson on medieval architecture. We focused on the Gothic Cathedrals built in the Middle Ages, and the advances in architecture which were necessary to build such tall structures.


    The first major advance was the transition from the rounded arch to the pointed arch. The pointed arch distributed the force of the ceiling and walls down toward the ground, and a bit outward. The old, Romanesque, rounded arch focused too much force outward as the columns grew taller. With the rounded arch, as the columns grew taller, the top of the arch would bow under the extreme force. And, as one arch bowed, the entire cathedral would begin to crack and crumble.
    As the pointed arch minimized the outward force, the outward force still existed. So, flying buttresses were created as supports for the arches. These supports connected to the arches about where the columns began and the arch ended. The point of connection was very important, because if the buttress was placed too low, the arch would still bow, and collapse. With the flying buttresses, walls could be supported from the outside; and, the force of the walls was aimed even more downward. The flying buttresses allowed the cathedrals to remain in equilibrium, balancing out all forces.


    And, what was the result of these advances?...................Cathedrals over 48 meters tall!


  12. goalkeeper0
    As APs are nearing closer, caffeine seems like the secret to success. Staying up late takes a toll on the body, and drains you of energy. Therefore, in the morning, it is very common to see kids and adults carrying around a cup of coffee or tea for the caffeine boost. Nobody wants to fall asleep in class. For those who do consume these beverages here is a disclaimer:

    Beware of water heated in a clean container in the microwave. Unlike when water heats up on the stove, water heated in a microwave can reach a temperature above its boiling point, and remain in liquid phase. This is called "superheating." Normally, when the temperature of the water exceeds its boiling point, the water slowly becomes a gas. But, in the microwave, boiling is hindered by lack of nucleation sites to form bubbles. A nucleation site can be a scratch in the container, a spec of dust, or any place where there is high surface area relative to volume. Also, the surface tension of the water in the mug suppresses the growth of bubbles. When the timer buzzes, and the mug is removed from the microwave, the water in the cup may appear placid, without bubbles (So, you think that the water's temp. is below 100 degrees Celsius). You are wrong, the water may be well above its boiling point. As soon as a powder such as a sugar or teabag is added to the water, the sudden addition of many nucleation sites can trigger an explosion of froth. Instantaneous boiling is induced. This can cause nasty burns to your skin.

    The "superheating" of water is easily preventable. First off, do not set the timer on the microwave for very long (over five minutes). Also, you may leave a nonmetallic object in the glass while it heats such a wooden stick to add nucleation sites. Lastly, stay away from heating and then reheating the same water multiple times in the microwave. Don't let this post scare you into never using a microwave again. Superheating isn't too common unless you set the microwave timer for 20 minutes instead of two, and then come back and find a very hot cup of water. Moral of the story: be safe when using the microwave.


  13. goalkeeper0
    Yesterday, the Girls' Varsity Soccer team started out with our first win! We scored a late goal with less than 2 minutes left in the game to make our way into the finals (of the tournament) on Saturday. After the celebrations and high fives, the referee came up to me and asked, "Have you taken Physics?" A bit taken by surprise, I responded "Yes." She went on to compliment the power and velocity of my punts, but she questioned the height. She believed, given the power behind the punts, that they should have greater horizontal range, and lower vertical distance. The ref believed that if I lowered my body, decreasing the projection angle, my punts would fly much past fifty yards. Her advice made me wonder, Is there an optimal projection angle? I looked online and found a study done in at Brunel University in the UK. Two men researched, and experimented to find the optimum projection angle to achieve maximum distance on a punt. To do this, they also took into account ball spin rate, projection height, projection velocity, foot velocity, and many more factors. What were their findings? To reach his or her maximum range, the average goalkeeper should have a projection angle of around 50 degrees. I definitely want to attempt this; but, the exact measurements might be a little tough, without the necessary technology. In practice, I will just experiment with many different projection angles.

    To read more in depth about this, I found the results of the study at Brunel University on http://www.jssm.org/vol10/n1/27/v10n1-27pdf.pdf.
  14. goalkeeper0

    Food of Flight

    By goalkeeper0,

    In Physics class we are currently working on a space exploration computer game named Kerbal Space Program. The purpose of the game is to build rockets or airplanes, think about money management, learn about space exploration, and achieve preset checkpoints. Lately, as our groups attempt longer and longer missions, the Kerbals are stuck in space for a considerably long time before returning home. The question has arisen, what do Kerbals eat while in space in order to survive? I am no Kerbal expert, and I have no idea what the Kerbals consume if they consume anything. However, this prompt inspired me to research a bit about space food in general.

    Typically, when one thinks of space food, tubes of unidentifiable jellies and freeze-dried snacks come to mind. Space food isn't known for receiving 5 stars. Food scientists have designed space food to be easily prepared, provide nutrients, and be edible while in low gravity. Foods which leave crumbs are not well-suited for space. Crumbs can float around the space craft and fly into unwanted areas. Loose debris such as crumbs can be harmful and dangerous to the crew. Today, the selections for space food are numerous in comparison to the tubed-applesauce of the past. To list some of the most popular space foods here they are-- Scrambled eggs, Chocolate pudding, Macaroni and Cheese, M&Ms, Pineapple, Swedish Meatballs, Yogurt, Tortillas, Shrimp Cocktail... So, if the mystery of space food turned your interest away from becoming an astronaut, think again. The food today isn't so bad. Food scientists with the help of physicists have mastered the art of eating in low gravity environments.
  15. goalkeeper0

    The WindTamer

    By goalkeeper0,

    When an adventuresome IHS student ventures out of the school building to the turf field, he or she passes the WindTamer and solar-powered lights. I do not know how much energy the turbine actually harnesses, but it is cool nevertheless. How does the WindTamer work? The WindTamer turbines create two vacuums which suck air through the blades, and the blades rotate (creating rotational kinetic energy). One of the vacuums is behind the blades, and the other is behind the turbine. The blades used in the WindTamer are very light, but numerous to produce the optimal amount of energy. The light blades move with the slightest amount of wind; so the device never wastes wind. The WindTamer definitely did not waste any wind this past week with Hurricane Sandy in town! It delights me that the engineers of the WindTamer took the wonderful birds of Irondequoit into account. The shape of the WindTamer, with housed blades, is supposed to reduce the amount of birds which fly into the device. If any brainless birds still fly into the WindTamer, natural selection is simply taking its course.

  16. goalkeeper0

    Multiverse?

    By goalkeeper0,

    In the realm of “big” things there is the world, the solar system, the universe, and then the…? Some scientists, primarily physicists, now believe in the existence of a multiverse. The idea of a multiverse has not been proven, but there is substantial evidence toward the theory. Some of the main points include:

    1.) The observable universe goes on for as long as light has had the opportunity to get in the 13.7 billion years since the proposed Big Bang. Beyond the visible universe there can be other universes lasting to infinity. This is because space and time are thought to go on to infinity.

    2.) Other universes could arise from something called “eternal inflation.” Inflation refers to the universe expanding very quickly after the Big Bang. Some believe that certain pockets stopped inflating, while others never stopped. As a result, separate “bubble universes” were created. In our universe inflation has ceased, and galaxies and stars formed as a result. Other bubbles may still be inflating.

    3.) It is possible that more dimensions exist to our world than the three of space and one of time that we know. The idea of parallel universes that remain just out of reach of our own universe is a theory. In a higher-dimension space other three-dimensional universes could exist.

    4.) Quantum mechanics support the existence of multiple universes. Quantum mechanics deal with probabilities and the idea that all outcomes of a particular situation occur somewhere in separate universes. In one universe you may chose to go left at a fork in the road, and in another universe you may go right.

    5.) Some believe that math is a “fundamental reality,” and our perceptions of the universe are "imperfect observations" of the mathematical nature of reality. Hence, many mathematical structures exist. The mathematical structure that makes up our universe may differ from mathematical structures in other universes.

    It’s hard to imagine that other universes may make up a multiverse; but, it is also hard to imagine that other universes don’t exist. Who is to say that we are part of the only universe? People may never really know or fully prove that we are part of a grand multiverse, but the topic will continue to intrigue scientists of all kinds.

    http://www.space.com/18811-multiple-universes-5-theories.html
  17. goalkeeper0

    A Pleasant Discovery

    By goalkeeper0,

    While studying for our midterm on Mechanics, I came to this brilliant realization.

    Realization: Physics with calculus is a lot easier when you know calculus

    Ok, this may seem like an obvious statement; but, when it clicks, it feels good. As I looked over some Mechanics Free Response problems involving derivations with drag force, I realized that they are not so bad after all. Now that all of us Physics-C students should understand integrals, differential equations, and integrating with natural logs, the Mechanics Free Response problems with calculus should seem manageable. So, for all of you who have acquired a phobia of drag force, take another look at the problems. It might surprise you that your background in calculus may cure your fear. Don't let drag force hold you back ; have confidence in this previously difficult concept!
  18. goalkeeper0
    Displayed in his videos for our current independent unit, Professor Walter Lewin has a strong interest in magnetic monopoles. Lewin repeatedly stated that proof of the hypothetical magnetic monopole would win the brilliant scientist a Nobel Prize. Because of his excitement toward this topic, I have researched a bit about the mysterious magnetic monopoles.

    Currently, it is believed that a magnet must have a positive, and a negative pole; the existence of magnetic dipoles has been elementary and common for years. No experimental evidence has been found to prove the existence of magnetic monopoles. However, many physicists still believe they do exist for theoretical reasons.

    New leads and ideas have led physicists to probe polarized rocks for magnetic monopoles. Polarized rocks buried deep within the Earth’s mantle are thought to contain magnetic monopoles. When the earth formed, and separated into chemically different layers, these researchers believe that magnetic monopoles “bound to matter that sunk towards the core.” This would explain why nobody has found magnetic monopoles in the Earth’s crust. Samples were taken from Antarctic and Arctic regions, but the elusive magnetic monopole still was not pinpointed.

    All in all, the race to find the magnetic monopole may never end. As the hunt stands now, physicists believe they are closer than ever to tracking down the hard-to-find magnetic monopole. Whether these monopoles are bound to matter, or travel freely through space, one can only theorize. If you want to make physics history, find the magnetic monopole.

    http://www.spacedaily.com/reports/Searching_for_magnetic_monopoles_in_polar_rocks_999.html
  19. goalkeeper0
    While exploring this lovely APlusPhysics site, I came across an article titled, "How Fast Would the Earth Have to Spin to Fling People Off?"
    I never thought about this question, but now wonder why I didn't. Oh wait, it's because the idea seems incredibly silly and impossible. Well, someone actually came up with an equation to answer this question.

    Here is the physics thought process:
    [ATTACH=CONFIG]644[/ATTACH]
    Ffake=an added force used to fix the accelerating reference frame
    Really, just two forces exist:
    Fground= normal force and Fgravity=mg
    [ATTACH=CONFIG]645[/ATTACH]
    If you want to solve using other locations on earth other than equator:
    [ATTACH=CONFIG]646[/ATTACH]
    [ATTACH=CONFIG]647[/ATTACH]
    So....Since changes in longitude impact this problem, every person on the world would not fling off at the same minimum rotational speed of the Earth. Those at the equator would fly off most easily. Luckily, we are not near the equator as seen by the weather today. At the equator the Earth's rotational speed must be 0.0124 rad/sec for people to tangentially fling off. The actual rotational speed of the Earth is 0.0000727 rad/sec. We should have nothing to worry about.

    source: http://www.wired.com/wiredscience/2013/03/neil-degrasse-tyson-still-complains-about-the-daily-shows-globe/
  20. goalkeeper0

    Senior Runs

    By goalkeeper0,

    As senior year comes to a close, brain space previously reserved for memorizing lists of vocab or challenging physics concepts has been filled with plots for senior pranks, senior runs, and so on. As of now, our senior runs have been quite brief, but I remember the senior runs of the past being both long and successful. As a freshman, I remember being caught in the hallway as I heard the shouts and footsteps of hundreds of seniors coming my way. Senior runs, or more like senior stampedes, can be heard from far away which is good so that small, tiny freshmen have time to hide in the bathrooms and not get trampled. Potentially, one caught in the middle of a senior run could get seriously bruised and battered. Stampedes are dangerous. I touched a bit upon stampede physics in my Black Friday post a very long time ago, but I found some more information about how physicists are studying crowd dynamics.

    Physicists look at fluids to help them understand crowd dynamics. Physicists have found that crowds behave as fluids with three different types of flows. The first type of flow is laminar flow. Laminar flow is a steady flow which resembles crowd dynamics when an area is undersaturated with people. The next type of flow is stop-and-go. Stop-and-go flow causes spurts of people to leave an area at a time. Waves are created in the crowd. The worst flow type is turbulent flow. Turbulent flow is the result of pressure buildups. Turbulent flow leads to "shock waves" which can push people up to 3 meters forward.

    I'd say that most senior runs do not reach the turbulent flow stage. However, given the velocity of the crowd, and the combined mass of the people in the crowd, these runs can definitely cause damage. The momentum of the stampede is enormous, and tiny freshmen are wise to seek shelter in nearby restrooms.

    http://physicsbuzz.physicscentral.com/2013/01/brazil-nightclub-stampede-trampling.html
  21. goalkeeper0

    Catapult

    By goalkeeper0,

    This is a picture of our beautiful catapult. The potential energy of the garage springs was converted into the kinetic energy of the arm. We positioned the beam across the catapult at about a 45 degree angle with the base. This angle maximized the range of the softball. For our first two launches, we had padding on the center beam, to absorb a bit of the kinetic energy of the arm, so the wood wouldn't break. But, for the third trial, we took off the padding, and the wood ended up cracking. The metal attachment on the arm also bent. After completing the calculations associated with the catapult project, the total initial velocity of the projectile was 17.96 meters per second, and it took 1.135 sec for our catapult to reach maximum height.
  22. goalkeeper0
    Every high school student treasures his or her first college letter in the mail. However, when the letters begin to consume your recycle bin, they become overwhelming. Each letter seems to advertise the same things: a nice campus, low student:teacher ratio, updated infrastructure, and groundbreaking research. So, when something different comes in the mail, it is exciting. Recently, I received a letter from the University of Akron advertising their Corrosion Engineering major, which is not offered anywhere else. As many of us taking AP Physics C intend to become engineers or scientists, I thought you may be interested in learning about Corrosion Engineering.

    *Corrosion engineers learn how to reduce the costs or corrosion, and design structures (roads, bridges, etc.) for greater performance and safety.
    *Currently, corrosion costs the US around $400 billion a year. Rusty columns, bridges, and pipelines are threats to society. Corrosion engineers work to improve public safety by assessing the damage done by corrosion, and slowing down the process of corrosion.
    *Corrosion engineering blends together chemical, electrical, civil, environmental, and mechanical engineering.
    *The demand for corrosion engineers is extremely high, as the US infrastructure continues to age.
    *Both the government and industries have donated large sums of money to this program at the University of Akron. Recently, BP donated $500,000. The major is up-and-coming.

    This is just a brief description of corrosion engineering. Overall, it seems like a great major if multiple branches of engineering interest you. Also, the job stability is tremendous as the instability of US infrastructure increases.
    If you want to learn more visit http://www.uakron.edu/corrosion/academics/curriculum.dot.
  23. goalkeeper0

    Faraday Cages

    By goalkeeper0,

    Faraday cages shield their contents from Electric fields. How does this work? Charge is distributed on the exterior of the cage, so that the Faraday cage acts as a hollow conductor. Therefore, since charge is only around the outside, the net charge inside the cage is zero; and, the E-field is zero inside the Faraday cage.

    But, what use is a Faraday cage? Well, this video excerpt from National Geographic's television show "Doomsday Preppers" will give you a whole new perspective on the value of Faraday cages and their potential value for the end of the world. When the end of the world does come, do you want your beloved electronics to be spared from electromagnetic radiation? If you are concerned, stop by the local thrift store like this woman and invest in a Faraday cage.



  24. goalkeeper0

    UV radiation

    By goalkeeper0,

    Pale people of the world, beware of the shining, warm sunlight! UV radiation, with a shorter wavelength than visible light, is absorbed by skin causing a sunburn and long-term skin damage. The Earth's atmosphere filters the majority of UV rays before they reach pasty humans; however, UV rays still penetrate the atmosphere. Exposure to UV radiation changes based upon altitude, distance from the equator, time of day, season and amount of cloud cover. At noon, with the sun high in the sky, sunscreen is heavily advised. How does sunscreen protect people from UV radiation?

    Sunscreen includes organic and inorganic compounds to reflect, scatter, absorb and release UV rays. Inorganic ingredients such as titanium dioxide and zinc oxide form a physical barrier between UV rays and skin. Because of this barrier, less rays penetrate deep layers of skin. Organic ingredients absorb UV rays and release them as heat.

    There are two different types of UV rays. UVA rays penetrate multiple layers of skin and cause long-term skin damage. UVB rays cause the visible sunburn and effect top layers of skin. Both types of UV radiation are bad. The SPF of a sunscreen is the measured UVB protection of the formula; there is no standard for UVA protection. A broad spectrum sunscreen protects against both types of rays. A sunscreen with a SPF of 15 means that one could spend 15 times as long in the sun before getting burned compared to the time necessary to get burned without sunscreen.

    Why wear sunscreen? Well, besides the fact that prolonged exposure to UV rays can lead to skin cancer and eye damage, UV radiation also can reduce the effectiveness of one's immune system. This fact seems strange. But, since UV rays displace or kill some cells necessary to trigger immune system responses, the body's ability to fight infections decreases.

    So, as we all await the end of school and the sunny days of summer, remember the importance of applying sunscreen!
  25. goalkeeper0
    While some are contemplating the end of the world, I am studying for physics. Here are the essential oscillations equations to know for our test tomorrow.

    Oscillations (Includes SHM, Springs, Pendulums):

    F=-kx
    xmax=A
    vmax=Aw
    amax=Aw2
    T=1/f and f=1/T
    w=angular frequency=2(pi)f=2(pi)/T
    v=wr
    Potential Energy= (1/2)kA2cos2(wt)
    Kinetic Energy= (1/2)kA2sin2(wt)
    Total Energy= (1/2)kA2
    x(t)= Acos(wt + phase shift)
    v(t)= Awsin(wt + phase shift)
    a(t)= -Aw2cos(wt + phase shift)
    Tspring= 2(pi)[m/k]1/2

    For use with pendulums only:
    Tpendulum= 2(pi)[L/g]1/2
    w=[(mgL)/(Ip)]1/2
    w=[g/L]1/2

    Also, from past units, the torque equations are handy, along with the moment of inertia equations.

    STUDY!!!

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