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prettybird

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  1. prettybird

    Split

    By prettybird,

    Last night, I went out and saw the movie Split. I was slightly intrigued by the reviews, and it was said to have a really surprising ending, so I put aside some of my personal opinions on the topic of choice and watched it. 
    It was a very interesting movie to say the least, and if you're planning on watching the movie, I would stop reading here, because in order to get into some physics I have to spoil the ending, which is entirely the best part.
    Okay, now that you're sure you want to continue, the movie is about a man with 23 distinct personalities inside him, which all take control at different times. While one, Barry, is in control, he kidnaps three girls. Three of the personalities (Barry, Ms. Patricia, Hedwig) believe in a figure called the Beast. The spectators find out that the Beast is not a figment of their imaginations, but actually a 24th personality that has super powers. Just by switching to this personality, the man's body becomes impenetrable and extremely strong.
    The only surviving girl, Casey, tries to shoot him with a shotgun and the bullet essentially bounces right off. That's where the physics comes in. How much force would a regular shotgun shell impart, and how strong would this man's skin have to be?
    A 1 oz. shotgun slug leaves the shotgun at 1800 fps, or about 550 m/s. This slug would weigh about .03 kg, giving it a momentum of 16.5 kg m/s. Assuming that the bullet was only in contact with his skin for .001 seconds, and it was a perfectly elastic collision, the force imparted onto his skin would be 16500 N. The only metal I could find info on was steel, and it can withstand 40 kN, meaning that his skin could withstand atleast half the force steel can.
  2. prettybird

    Stardew Valley

    By prettybird,

    One of my more recent favorite games has been Stardew Valley. It is essentially an updated version of the game Harvest Moon, which originally came out in 1997 on the Gameboy, which is what I originally played it on. It is a game where you inherit a farm from a dying relative, and you come to find it overrun with weeds, trees and rocks. You slowly clear it out, plant crops and adopt animals. You can also mine and fish, and you slowly build relationships with the people in the town by joining them at festivals or bringing them gifts. You also have the opportunity to start a family.
    For the most part, the game seems fairly realistic. You have to bait your fishing rod, it takes alot of hits to chop down a tree and you lose energy the more you preform a task. However, the mine introduces something that really breaks physics in this game. The first mine you journey into have 120 floors, and when you reach the bottom you receive a skeleton key. Once you unlock the desert, you have the chance to open another endless mine
    Two things here are the problem. One, this mine is truly endless, and at some point you would not be able to go any farther because you would hit the center of the earth and just burn up.
    Also, you can find holes which allow you to drop down levels. Not a ladder, like how you progress most of the game. It is a literal hole you must jump down. I have seen someone jump down 11 floors at one time. Now, it does take away some health, but assuming that each floor in the mine is around 6 meters minimum, you would fall 66 m, meaning you would be falling at around 36 m/s by the end of your fall. This would surely cause a bone to break, but you come away unscathed. 
  3. prettybird
    Overall, I have been enjoying the first few days of physics class and reviewing the content we learned last year. It was generally pretty easy. However, let me talk about scientific notation. I thought I was good at it before this year, but I guess not. I read the first chapter of the textbook and watched the first lecture and figured I was well prepared to start the intro WebAssign. For some reason, the scientific notation problems gave me the most trouble. I re-read the chapter, and figured I'd give it another go. Again, no luck. I followed all the rules in the textbook and I still could not get these problems to work. I finally decided to type it all into my calculator exactly as the problem stated just to see how these ended up and still I could not get the right answer for the last one. Somehow, I cleared the entry from my calculator and when I finally realized I had forgotten a negative sign somewhere I had to type it all in again, which took another 10 minutes.
    Overall, Physics - 1, Me - 0.
  4. prettybird
    I'm not talking about cannonballs like what you shoot out of a cannon. That's obvious, a huge object is hitting you at a large velocity therefore there's a huge force transferred to your body. 
    I'm talking about the cannonballs you do when you jump into the pool with your friends on a warm summer day. (Which we're all looking forward to after this winter). 
    When you jump into a pool, the water has some amount of surface tension to oppose objects from entering it. When you dive in with your hands out, you break that surface tension before the rest of your body enters, and so only your fingertips feel a force. When you do a cannonball, half of your body feels the force, leaving that stinging feeling.
    This is also the reason why when people fall or jump off bridges, they often say the impact kills them (not drowning) because the surface tension applies such a huge force.
  5. prettybird
    If a tree falls in the forest, and no one is around to hear it, does it make a sound?
    When a ball hits the ground or an axe hits a tree, we can hear a noise signaling this collision. Obviously, sound waves are produced, but where exactly do they come from? 
    When two objects collide, one of two things can happen: an elastic or inelastic collision. In the case of elastic, no kinetic energy is lost. Inelastic, however, involves a loss of kinetic energy. Where does it go?
    Part of it goes to heat, but another part of it causes the sound waves to be produced because they need energy. When two objects collide, the molecules of the object vibrate a little, which in turn vibrates the air molecules, creating a longitudinal wave. 
    So, if a tree falls, it does make a sound because the laws of physics don't stop just because there isn't a human to watch it. 

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