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  2. I wonder how they could still throw the spear straight. It seems much easier to hunt with "guns and cool stuff"
  3. I wonder who gave you the idea to write a blog about archery...
  4. I hope that you get well soon! I never knew that MRI machines produce a magnetic field.
  5. Last week
  6. What an incredibly skilled athlete!
  7. Interesting bro. Cool when chemistry and physics cross over
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  9. You may have noticed it’s been a LONG time since I’ve updated this physics education blog. More likely you haven’t noticed, because it’s been a LONG time since I’ve updated this blog. This hasn’t been due to a lack of topics to write about, but rather, it’s been a conscious choice to plow full steam ahead on a project that began in June of 2013 and that I’m thrilled to announce is now available, The AP Physics C Companion: Mechanics. But first, some background. Traditional AP Physics C As a teacher of calculus based physics (AP Physics C – Mechanics and AP Physics C – Electricity and Magnetism), I’m faced with a very unique challenge in those courses. I typically enjoy classes of bright, motivated students who are preparing for careers in engineering, science, medicine, and other technically challenging fields. And I love teaching the content of these courses — the level of technical challenge keeps me motivated, and I love the highly mathematical nature of the course. In teaching the class, however, what I found is a very aggressive schedule to fit both courses into the school year, and my students are co-enrolled in calculus (which means they typically need to solve calculus problems in physics before they’ve been introduced to the calculus in their mathematics classes). Further, teaching in a traditional style, I found that most topics fit fairly well into our 42-minute periods. Students come in to class, begin with a warm-up question tied to the previous day’s topic, which we spend a few minutes reviewing, then I have time to present a single topic with an example or two each day. If we don’t take any breaks, and throw in a quiz or test every couple weeks, as well as some fairly straightforward lab activities, we JUST barely get through all of our material in time for the May AP exams. What I especially enjoy about this class and this method of teaching, however, is the face-to-face time with the kids during the daily lessons. Class sizes for AP Physics C is typically small enough that we have a very informal style that is warm and inviting, yet challenging for all. The students enjoy the class, taking notes from their seats each day, and doing book problems and old AP problems for homework in the evenings. And our AP scores each year are solid. In September of 2011, however, I decided to try something different. I wanted to get away from the teacher-centric model, as I realized that I was the hardest working person in the classroom. This contrasted with the best teaching advice I ever received, when our assistant principal and my mentor explained that I should strive to “Look like the laziest teacher in the building while the students are in the classroom, and the hardest working teacher in the building the moment they leave.” What he meant was students should be doing the work in the classroom, especially as I continuously espoused my belief that physics is something you do, not something you know. Although the students were doing OK in their passive roles as notetakers, this was a credit to the strength of these students, not my teaching. A New AP Physics C Methodology Instead, I began to imagine a classroom in which students directed their own learning, building lifelong learning skills that would serve them well outside the narrow discipline of future physics courses. With the blessings of our administration, I undertook a giant experiment in the classroom. We went through the year with the goal of having zero teacher lectures. Instead, I completely “flipped” the classroom. Students were expected to watch video mini-lessons on topics outside of class, as well as read the textbook and take notes, saving classroom time for group discussions and problem solving, hands-on lab activities, and deeper dives into topics of interest. I ended up going back to traditional lectures on two topics — Gauss’s Law and the Biot-Savart Law, but for the most part the class ran independently. I built up “packets” of assignments, practice problems, labs and activities for each unit, and students worked at their own pace (within reason) through each unit. Unit exams were given when students said they were ready, with multiple re-take opportunities. This evolved into a self-paced course, and at the end of the year, I found AP scores were significantly higher than in past years, which in retrospect shouldn’t have been surprising. Teaching in this more hands-off manner is very uncomfortable, however. I “feel” like I’m doing a great job when I’m working hard, presenting great lectures, and interacting with the students. Stepping back and watching the students work, only getting involved to ask the occasional question or provide some basic clarification and support is extremely challenging. Given the results, though, I tried it again the following year. Same result! These classes were regularly polled for feedback on the course. General observations were that many students felt more intimidated and lost at the beginning of the course. As well, there were several points throughout the year in which the students felt quite frustrated. Polls at the end of the year, however, indicated students felt very confident in their self-teaching abilities, their ability to work through challenges they initially thought impossible, and their comfort level with their preparation for future studies. The most common opportunity they identified for improvement — learning how to read the textbook. In an effort to address this, I’ve implemented a variety of changes in my classroom. First off, we take some time at the beginning of the year and again after mid-terms to talk about and practice strategies for reading a technical text. We also take some time to talk about how to actively use the video lessons and example problems so that study time is efficient and productive. The AP Physics C Companion: Mechanics Finally, I started work on a “companion” text to the AP Physics C curriculum, focused on distilling down the key points from the text and illustrating them with a variety of applications. Not really a review book (though it could be used in that sense), but rather a cleaned-up version of instructor notes for the course that could be applicable to any calculus-based mechanics course. A large focus of the book is trading off technical complexity for illustrated application of concepts, including justifications for problem solving steps in the problems themselves, and well-documented problem solutions. I’ve been using the notes and draft chapters of this book for several years in my classes, which has allowed me a “test run” of various sections and the opportunity to see what works with students, and what needs further revision. The final result, I’m excited to say, is now available as “The AP Physics C Companion: Mechanics.” It will first be available in black and white print editions from APlusPhysics.com and Amazon, as well as a full-color PDF edition on APlusPhysics.com. Shortly thereafter, print editions (both color and black and white) will be available from any retailer, including Amazon and Barnes and Noble. Finally, bulk purchases will be available directly from sales@sillybeagle.com (Silly Beagle Productions) at substantial discounts. Where’s the E&M Book? I’ve already been asked repeatedly if there’s an E&M version planned. The answer is rather convoluted, however. The E&M version is half done — the draft is complete as part of my class work and has been for more than a year. I haven’t typeset it yet, however (probably a 6-12 month project), or worked on the graphics for a few reasons. First, it is a huge investment of time to do so, which puts other projects on the back burner. Second, the market for such a book could be pretty small. As only 27,000 students took the AP Physics C: E&M exam last year, that’s a very limited market to cater to. Though the book would be appropriate for an introductory calculus-based E&M course, a very significant portion of students taking the E&M exam would have to purchase and use the book in order to recuperate the costs involved in putting out the book (which are substantial). As most any science author will tell you, there’s not much profit to be made in writing these types of books, and margins are mighty slim. It’s a labor of love because you want to help students (yours and others). I’m already pushing the limits of ‘wise decisions’ in marketing a book to the AP-C Mechanics market (53K test takers last year), and hoping it at least breaks even. Before making any commitments to an E&M version, I want to obtain feedback from the mechanics version — are students and instructors finding it helpful, what is a reasonable percentage of the market to anticipate, would it at least break even, and how is the new format received (fewer pages, larger format and type, color vs. B&W, etc.) Given all that, I imagine it’s probably likely at some point I’ll get to work on it (after every book I tend to think I’m done, then eventually change my mind and start on another one). However, it feels good to “fool myself” for awhile and pretend I’m done while I work on updating the APlusPhysics site, continue work on instructional videos, and perhaps get to bed a little earlier in the evenings. For now, however, I’m excited to announce the release of The AP Physics C Companion: Mechanics. Hope you enjoy it as much as I enjoyed putting it together! *AP and Advanced Placement Program are registered trademarks of the College Board, which does not sponsor or endorse this product. The post New AP Physics C Mechanics Book Release appeared first on Physics In Flux.
  10. As a saxophone player, I have always wondered how exactly sound waves work and why some notes sound good together while others don't. For example, when notes that are a half step apart are played simultaneously, "wobbles" are produced. If two sound waves interfere when they have frequencies that are not identical but very close, there is a resulting modulation in amplitude. When the waves interfere constructively, we say that there is a beat. The number of beats per second is known as the beat frequency, which is simply the absolute value of the difference in the frequencies of the two pitches. From a music theory standpoint, intervals can be referred to as consonances or dissonances. Consonances occur when tones of different frequencies are played simultaneously and sound pleasing together. Dissonances occur when tones of different frequencies are played simultaneously and sound displeasing together. According to a lecture by Professor Steven Errede from the University of Illinois, the Greek scholar Pythagoras studied consonance and dissonance using a device known as a monochord, a one stringed instrument with a movable bridge, which divides, "the string of length L into two segments, x and L–x. Thus, the two string segments can have any desired ratio, R = x/(L–x). When the monochord is played, both string segments vibrate simultaneously. Since the two segments of the string have a common tension, T, and the mass per unit length, mu = M/L is the same on both sides of the string, then the speed of propagation of waves on each of the two segments of the string is the same..." Basically, the ratio of the lengths of the two string segments is also the ratio of the two frequencies. Consonance occurs when the lengths of the string segments are in unique integer ratios. To learn more about the physics of consonances and dissonances, read his lecture here: https://courses.physics.illinois.edu/phys406/lecture_notes/p406pom_lecture_notes/p406pom_lect8.pdf.
  11. How many IQ point do you think the ball knocked out of you??
  12. And keeps your fries tasty!
  13. Nate Stack can't guard me. If he trys he will get crossed over
  14. One of the most well known track and field events is the long jump. This event is where an athlete sprints as fast as they can toward a line then jump into a sand pit. Several simple kinematic concepts are displayed in this event. Firstly the distance traveled by an object is proportional to the velocity of an object. This translates to the long jump in that the faster the person is moving as they approach the point where they have to jump, the farther they will travel. Also the length of the jump will be determined by the angle the jumper makes with respect to the ground. The ideal angle for this is 45 degrees, because this produces an ideal balance between velocity going in the x-direction and the y-direction. Therefore any good long jumper will have both good spped as they approach their jump as well as the skill to propel themselves at a 45 degree angle to the ground in order to produce the maximal distance out of their jump.
  15. In soccer the power of your shot can be the difference between a very good goal and a shot the goal keeper having no problem with the shot. But what goes into creating a more powerful shot? What determines this is the amount of torque one can create when you move your leg in the cyclical movement when striking a soccer ball. In the equation, T = F * r , you are clearly able to see that the amount of torque created by your shot is determined by the length of your leg that you are pivoting around in a partial circular motion. This brings to the soccer legend, Zlatan Ibrahimovic. He stands at 6' 5" much taller then most all soccer players. As well as a tremendous amount of skill, what sets him apart as an incredible player is his physical attributes. The longer leg that he has to strike the ball creates more torque in the circular motion of his leg. He may have the same amount of force being put into the shot however because torque is directly proportional to radii, Zlatan can create an extremely powerful shot relative to his peers.
  16. In the spirit of the new resident evil game coming out very soon, it should be interesting to find out how many characters should have died in the previous game in a helicopter crash. Throughout Resident evil 6, the are a few helicopter crashes, and in the usual horror game scare tactic, everyone but the main characters die in these crashes. But should your characters have lived? There is an average of 1.44 fatalities per hundred thousand hours flown in a helicopter, and you can probably make a safe guess that if your helicopter crashes, you're at much higher risk for dying. Although there are countless factors that play into how a helicopter crash will turn out, lets just break it down to its simplest form, how high up would a helicopter fall from, and how much does a helicopter weigh? An average cruising height for a helicopter is around 2000ft or 609.6 meters, and an average helicopter weighs about 10000 pounds or 4535.924 kilograms. So, with those estimates, a helicopter would hit the ground with roughly a force of 2765099.27 newtons, and while it is definitely difficult to say how much force it takes to kill a person, it is most likely safe to say that this much force spread out across your entire body as well as the environment around you is lily enough to kill you. So based on this, things aren't looking too good for our heroes Leon and Helana, especially considering even if they do somehow miraculously survive the initial impact, they would still have to immediately begin fighting zombies, and with those odds, chances of survival are looking pretty poor. So, is it possible to survive a helicopter crash? Yes. Is it likely? no. Falling to the ground in a 10,000 pound box of death is generally not very good for your health and should be avoided at all costs if possible.
  17. Guitar pickups are really interesting technology. most people have seen or played an electric guitar, and the way that the guitar is able to transmit sound to the amplifier is through the pickups. in essence, a guitar pickup is a set of magnets wrapped in wire. while there are different types of pickups such as humbuckers, single coils, and p90's among others, they all operate in generally the same way. It all starts by playing a string on the guitar, and from there, the physics really gets interesting. the permanent magnets in the pickup create a magnetic field, and the vibration of the string creates a flux through the magnetic field, which then creates a voltage in the wire which is then transmitted to the amplifier via a quarter inch cable so you are actually able to hear it at a reasonable volume. Other types of pickups such as humbuckers, offer specific benefits not enjoyed by single coil pickups, Humbuckers feature 2 coils that are wound opposite eachother as well as having every other magnet have the polarity flipped so that when interference noises are picked up by the pickups, the noise is distributed evenly throughout all directions, and the interference noises are then cancelled out by the opposite wound coils since they have an equal amount of interference distributed throughout them in opposite directions. Guitar pickups are really a very influential invention, allowing new cool sounds to be made with a guitar, creating the basis for entire genres of music.
  18. In Battlefront, the main infantry weapon is a gun that fires lasers. Though it would be amazing, this will most likely never be a reality because of a few properties of light: refraction and scattering. Light can bend, and will in foggy or rainy conditions. Also, it will disperse as it travels, reducing the intensity. Another reason why it is impractical is the energy requirements for a laser beam that can kill. To create a laser beam that is strong enough to kill, 24 Kg of batteries must be used. This is extremely impractical compared to lighter magazines which can hold a large amount of bullets. Light also has a velocity that is larger than escape velocity, meaning that it will not drop and will just shoot off into space for all eternity. Until light can be harnessed more efficiently or a more compact source of energy can be found, i do not believe that we will be seeing laser rifles anytime in the near future.
  19. Besiege is a game where the object is to build siege engines to take down armies and castles. One extremely effective siege weapon is the catapult, which is loaded with physics. Catapults can be loaded with projectiles that when released are launched at extremely high speeds and over long distances. How a relatively small mechanism can create such large amounts of force and speed is similar in some ways to the crossbow, but different in other ways. With a bow, the string can be drawn back at different distances and can be made with different thicknesses. With a catapult, the exact same amount of potential energy can be transferred to the projectile every time causing much more consistency. This is because of a counterweight, which is placed on the opposite side of the lever as the projectile. This counterweight must weigh much more than the projection itself in order to cause an imbalance, much like a teeter totter. This causes a much higher launch speed because of the mechanical advantage created. Besiege allows you to build catapults, which can fire stones so fast that they can break through castle walls and flatten armies showing the raw power that a knowledge of physics can bring.
  20. A game that me and my friends have been playing a lot recently is called Gang Beasts. It is an arena fighting game where the object is to be the last man standing. What makes it entertaining is that the characters that are fighting are rag-dolls, which means that you have little control over their bodies. They move fluidly and are not stiff, which is very entertaining to watch when it a fight to the death between 8 players. In order to get another player out, you have to punch and kick them until they are knocked out. Then you have to grab them, pick them up, and throw them out of bounds. This all seems very simple, but each limb is individually controlled so it is very difficult. With skill however certain things can be done such as swinging someone around your head in order to throw them farther, or grabbing a part of the map in order to save yourself from falling. The game is 100% physics based, but is extremely hard to explain with words. It is so simple that it is fun and difficult, but makes for some hilarious moments. I mean, whats more fun than dragging your friends limp body over a ledge?
  21. The Dark Souls series is known for being extremely difficult. This is because of the complexity of the combat and the strength of the enemies in the game. When fighting an enemy, the only way to dodge its weapon is to perform a tuck and roll. The tuck and roll is the core of all combat in Dark Souls. It gives you a small window of invincibility which can be used to re-position yourself behind an enemy or give you just enough time to drink a crucial health potion. At first glance however a tuck and roll looks painful, but when examined closely it can be seen why a tuck and roll is a genius use of physics and the human body in order to mitigate pain. When jumping from a building, all of the force will be exerted upon your feet and legs when landing which is extremely dangerous. If you tuck and roll however, the force will be dispersed evenly across your body, allowing you to jump from distances that you couldn't before. This move is used by people who do Parkour, or freerunning.
  22. The Skate series has taken over skating video games. In Skate, you skate around town doing flips, grinds, and ride ramps doing cool grabs and holds. Behind all of the fancy tricks is a skateboard. Skateboards broken down simply are boards with 4 wheels, with each end bent up slightly. In this blog, i am going to break down the physics of a kick flip, and how it is possible. First, the skateboard gets into the air through an Ollie or bunny hop. Second, the skater will push on opposite sides of the board giving it a rotation around its center axis. If timed correctly, the board will complete one full rotation before landing back on the ground wheel side down. What looks simple is actually a very difficult series of events that must be timed and executed perfectly, or else a wipe out will happen.
  23. One mobile game has taken over IHS: Clash Royale. Most people either play it because the like it, or just simply have it on their phone because one of their friends made them download it. Regardless, one of the most controversial aspects of the game is filled with physics that is taken for granted. The X-Bow is a crossbow that fires huge arrows at outrageous speeds. The mystery behind a crossbow is how such a simple mechanism can create such speed and force behind an arrow. The answer is simple: Potential Energy. When the string of the crossbow is pulled and locked back tightly, work was done on the string giving it stored potential energy. This potential energy will be converted into Kinetic energy in the arrow when released, sending it flying. This explains why the arrow flies faster the tighter the bowstring is, or if you pull it back farther. A higher potential energy inevitably means a higher kinetic energy.
  24. In arguably the greatest gaming series of all time, The Legend of Zelda, one of the core weapons is based solely off of physics: The boomerang. The boomerang is used to kill enemies, retrieve items and rupees, and best of all can be used infinitely due to the fact that it always comes back to you. The key to a boomerang returning to the thrower is a phenomenon known as gyroscopic procession. This is where one wing is moving through the air slightly faster than the other, creating unbalanced forces. As the top wing is spinning forward, the lift force on that wing is greater and resulting in differing forces that gradually turn the boomerang. This causes it to loop around in a circle, and return to the thrower.
  25. In GTA V, physics is a large factor in almost every part of the game. One example is when driving cars in GTA, you can reach some fairly impressive speeds. If you get into a car and start driving immediately, your character doesn't put on a seat belt which is a recipe for disaster. If you crash while driving at an insane speed, you will fly through the windshield and out of the car. This is because of inertia. As everyone knows, inertia is a property of matter. It is a measure of a resistance to acceleration based off of mass. When driving at fast speeds, the car is pushing you at the speed. When the car suddenly stops, your body wants to keep moving forward due to its inertia. Because of the lack of a restraint, your character flies through the windshield and skids across the road. Should've buckled up.
  26. The Battlefield series is widely known for being realistic, intense, and hardcore. Every single aspect of the game is impressively real, even down to how bullets behave when shot. Sniping is one of the most challenging aspects of the game due to the behavior of bullets. When shot, a bullet encounters air resistance and gravity, giving it a downward flight pattern. The air resists its forward motion, giving it a negative acceleration in the x direction, while gravity give the bullet a positive acceleration downward. This is commonly known as "bullet drop", so one must raise the cross hairs above the target depending on how far away it is to account for it. Binoculars can be used to measure the distance, and sights can be adjusted accordingly as well. The implementation of physics into war simulators makes an already realistic and hardcore game that much more intense.
  27. In the interest of simplicity, we're going to talk about how a co2 powered blow-back style paintball gun works, because an electric paintball gun has so many complex parts, each one could have it's own explanation. so, Simply put, a co2 tank is screwed into the back of the gun, the gas flows through the gun, and is used to move the bolt back and forth, creating enough pressure behind the ball so send it flying out of the barrel. So, since this style of paintball gun is mainly gas through (no air regulation between the tank and the rammer), the main part that must be explained is the poppit valve. When pressure from the gas is released into the lower chamber when the trigger is pressed, the rammer is compressed back against the spring, moving the bolt backwards and allowing a paintball to enter the upper chamber the bolt then slams forward into the ball, followed by a puff of gas which propels the ball out of the barrel at about 300ft/s.the force from the gas being released again pushed the rammer back, compressing a spring, which will then repeat the whole process over again as the trigger is pulled again. This is where the type of paintball gun gets its name of "blowback style" as the gas released with each trigger pull "blows back" the rammer into place, resetting it and preparing it for another shot without the user manually having to move anything between shots.
  28. Swings are found in children's playground and are very fun and enjoyable. They work just like a pendulum. A swing converts potential energy into kinetic energy as you swing. When you first get on the swing and take step back as far as you can to get the best swing you build up potential energy. When you pull your feet up and begin to swing your potential energy is converted into kinetic energy. When you reach the the maximum height form swinging your potential energy is built up and again is lost when you swing back down. By swinging higher you build more potential energy and swinging faster makes more kinetic energy. So remember that the next time you start swinging all's your doing is converting energy.
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