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SgtLongcoat

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  1. SgtLongcoat

    WoP #4: Car Crashes

    By SgtLongcoat,

    A couple days ago, I was waiting to be picked up (since I'm a seventeen year old chicken who still doesn't have his license), and I unfortunately almost witnessed a car accident. A child, maybe four or five years old, went to chase after a ball which went across the street, and the driver couldn't see him because there was a parked car in the way. I tense up because I'm about ready to bolt over and help the kid, but luckily the driver stops about a yard away from hitting the kid. He's one lucky kid.
    The weird thing about this, though, is that the force of friction acting on the car to move it forward before the brake is applied is the force of static friction, which is greater than the force of friction which acts to bring the car to a stop after the brake is applied, that of kinetic friction. This means that, in order for the car to come to a stop, the brake would need to be applied for a longer amount of time than the gas would to bring it up to speed, being kinetic friction has a lower acceleration than static friction.
    In addition, the impulse the kid would've felt had he been hit would likely be enough to cause serious injury, considering the magnitude of the momentum of the car compared to the child's momentum in the direction of the car's motion (~0 kg m/s), and the fact that the car's velocity wouldn't change much due to the child's relatively small mass compared to the car. I truly am glad the car stopped in time, because human road kill isn't something I ever want to see.
  2. SgtLongcoat
    Terraria; one of my favorite games of all time. I've played through it more times than I can count, and have logged more hours into it than I care to admit. The game is a sandbox game full of crazy bosses and easter eggs. Needless to say, it tends to have its own spin on the laws of physics, but almost always these spins are based on real physical laws. One such way the game has fun with physics is with its reference to Valve's Portal series: the Portal Gun.
    The problem isn't that the gun allows for instant teleportation (the game already has teleportation pads and potions). The problem lies in the affect of holding the gun. When holding the gun, the player's terminal velocity changes from 51 MPH (22.79 m/s) to 179 MPH (80.02 m/s). Assuming that the net force on the object is mg-bv, which should be equal to 0 at terminal velocity, meaning terminal velocity = mg/b, and g and b are constant, this means that the portal gun would be two and a half times the mass of the player. Though this would make the player insanely strong, this isn't entirely unrealistic.
    However, this assumes that gravity is constant. When holding the gun, the time taken to accelerate to this new terminal velocity is the same as it would be to accelerate to the former, meaning the acceleration due to gravity is what increases 3.5x. As such, it can be safely assumed that the portal gun, as it exists in Terraria, breaks laws of physics. Though, in a video game, which is more fun? Being bound by the laws of physics, or being able to have some fun with laws that we can't change in real life?
  3. SgtLongcoat
    Undertale… where do I even begin? To describe it simply, it’s a game which shows us that there are consequences to our actions, and attempts to show that there are other solutions in video games than violence. It’s one of the most amazingly funny and heart-wrenchingly emotional experiences you can get out of a 2D game. That being said, mostly for the rule of funny, the game tends to ignore the laws of physics.
      One of the most blatant examples of this occurs during the game’s pacifist route, where one of the characters, a skeleton named Papyrus, jumps out of a closed window, causing it to shatter. The problem? By jumping out the window, the force Papyrus exerted on the window would have been directed outside the house, meaning the shards of glass would have landed outside. Despite this, when jumping, the ENTIRE window breaks inwards, and lands INSIDE the house.
      There are several tough bosses in this game which drive people insane, some of which also break the laws of physics… or blatantly ignore them… But the fact that one of the easiest, kindest bosses in the game can so casually break the laws of physics just goes to show how dangerous he may be…
  4. SgtLongcoat

    WoP #1: Jelly Cat

    By SgtLongcoat,

    So, I went to RIT for a college visit not too long ago, and they played the above (slightly goofy) video about creating perpetual (never ending) motion by combining two principles derived from urban legends. The first is that a cat, dropped from any height, will always land on its feet, and the second is that a piece of toast with jelly on it will always land jelly-side down. The video goes on to state that, by spreading jelly on a cat's back, the cat will be unable to land both on its legs and jelly-side down, and will spin indefinitely. The video goes on to state that this could be used to power a train system by using the cats as a form of wheels. Unfortunately, there are several things wrong with this videos "theories."
    First of all, the mass of the jelly is on a much smaller order of magnitude of that of the cat. As such, the mass of the jelly would move the cat's center of mass a noticeable amount, meaning any forces acting on the cat-jelly system should still have the same effect as those acting on an un-jellied cat. Assuming a cat will always land on its feet, this means that even a jellied cat will always land on its feet, and the jelly will not have affect that in the slightest.
    Second, assuming the cat would enter a state of perpetual motion, using it to move a train would still be impossible. In order to move a train, the cat would have to apply some force to the train, and the train would therefore have to apply some force to the cat. Assuming this is the case, the cat would likely have a normal force acting on it from the train, and therefore, a force of friction. As such, considering the mass, and by extension, weight of the train (which would be part of the normal force), the force of friction (which opposes motion) would likely be of a much greater magnitude than any other forces acting on the cat, and, therefore, the cat would be decelerated until it eventually reached a stop. Therefore, it would be impossible to use a cat to power a train system.
    Finally, the weight of the train would crush the cat. Why doesn't anyone want cats to live?
  5. SgtLongcoat

    Introduction

    By SgtLongcoat,

    Hello, and welcome to the World of Physics. Considering this is my first post, I feel it necessary to describe myself a little. First and foremost, I'm a huge fan of gaming, so a majority of my posts will likely discuss their insane simulations of physics. In addition, I'm a Boy Scout, currently working towards my eagle rank. I'm great with technology, and took several classes in programming over the course of my high school career. In the future, I hope to study programming further, as well as game design, and I would ideally like to break my way into the video game industry. For a slightly more realistic career choice, I simply want to be a computer programmer. This is part of the reason I'm taking Physics C this year. Especially in the case of game design, understanding physics allows for the creation of much more realistic animations and events. On the other hand, I also really like learning how a lot of stuff works. This year, I hope to learn much more about physics on the quantum level, as I find the lack of decisive data on the field interesting. Aside from that, I have no idea what to expect from this class, so I guess I'm excited simply to see what it holds. Well, that's the end of that. If you managed to sit through that entire wall of text, you have my utmost respect. Take care, and you'll be hearing from me again soon.

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