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jrv12

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About jrv12

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  1. What's at the End of a Rainbow?

    Double rainbows are very cool to see, especially since the first one is so bright!
  2. Second Quarter

    This quarter was definitely stressful, but now we're halfway done with senior year!
  3. The Many World Theory

    Wow this is crazy to think about!
  4. Archery: The Physics of the Bow

    Archery is one of my favorite P.E. units too!
  5. A Heated Runway?

    I read something on this before and it would be very interesting if there was a way to implement the technology into all of the roads throughout the country!
  6. The Physics Behind Curling

    I never thought about all the physics involved in curling!
  7. Air Resistance Tests

    Last night my younger brother was watching one of his favorite shows: street science. I happened to walk in the room as they were doing a Galileo-inspired experiment where they were dropping different objects from a crane to show the effects of gravity and air resistance. At first, they dropped a basketball and a bowling ball from a height of 50 feet. Physics tells us that both objects should hit the ground at the same time because in free fall the weight of the object doesn’t matter. However, the bowling ball hit the ground before the basketball, showing the effects of air resistance. Next, they dropped two bowling balls from the same height but with different weights. They wanted to show that, while the shapes of the balls were the exact same, they still wouldn’t land at the same time. They heavier bowling ball took less time to hit the ground than the lighter one, but they were closer in time than basketball and bowling ball were. Finally, they dropped a truck and a refrigerator from a height of 50 feet. They hit the ground at the same time because in that little of a height with that much weight, air resistance does not have much of an effect. If the truck and fridge were dropped from much higher, they would not have hit the ground at the same time because of air resistance. It was pretty interesting to watch the effects of air resistance on different objects!
  8. *More spoilers ahead* One of the big scenes of the movie takes place when Chris Pratt’s character Jim is blasted away from the ship while saving everyone on board and his tether connecting him to the ship breaks, leaving him floating in the depths of space forever (or so you think). Many of the scenes involving tethers are actually scientifically correct. Jim and Aurora (Jennifer Lawrence) float with ease while connected to their tethers, and don’t interfere with any of Newton’s laws. While connected to their tethers, they experience no tension because there are no external forces. Another big scene in the movie is when Jennifer Lawrence’s character Aurora is swimming in the pool when, all of a sudden, the power goes out and there is no longer any gravity. Instead of the water floating up from the pool in droplets and Aurora floating into the air, the water moves up into the air all together, with Aurora stuck inside. This is because of the large surface tension of the water, it all sticks together in zero gravity and traps Aurora in the middle of it. Here’s the zero gravity scene:
  9. This past week, I finally was able to watch the movie Passengers starring Jennifer Lawrence and Chris Pratt. As I was watching, I couldn’t help but notice all of the physics involved. *If you are planning on ever watching this movie, continue reading at your own risk, spoilers may be included.* The story takes place in the future, where two of the characters wake up 90 years early from hibernation on an interstellar spaceship. The spaceship the characters are on creates artificial gravity by rotating. The way the gravity is created is the centripetal force from the rotating spaceship. The gravity felt is from the normal force produced, and Newton’s second law states that the gravity created is equal to the centripetal acceleration. The centripetal acceleration is equal to velocity2 / radius. So, a higher centripetal acceleration is created by using a greater velocity or a smaller radius.The Coriolis effect is another way the gravity is felt, which gives an apparent force acting at a right angle to the motion and the rotation axis, creating the effect of gravity. At certain times during the movie, the artificial gravity disappears when the power on the spaceship malfunctions. When there is no power to rotate the spaceship, there is no gravity felt on the spaceship.
  10. Dog Whistles

    The other day my younger brother was using a new dog whistle app on his phone to make tour dog (and me!) go crazy. However, my dad was in the same room and he couldn’t hear the annoying high-pitched sound at all, so my brother was able to get away with continuing the high-frequency dog whistle sound. The highest frequency dogs can hear is 45 kHz, while a child’s limit is 20kHz, and a middle-aged adult’s is 15kHz. Dog whistles range from about 20 to 54 kHz, so it makes sense that I was able to hear the whistle while my dad was not. The equation for frequency is 1/period of the soundwave, or velocity/wavelength. So, higher frequencies are created by a greater velocity of the wave and a decreased wavelength. Waves with different velocities can still have the same frequency if the wavelengths are proportional, and waves with different wavelengths can have the same frequencies if their velocities are proportional. In the video below, it shows the sound waves at different lengths, illustrating the differing velocities and wavelengths at different frequencies – and the different sounds we are able to hear.
  11. Rip Currents

    When I was at the beach in North Carolina over the summer, for a couple of days there was a sign outside the lifeguard stand that said WARNING: RIP CURRENT. Now at the time I wasn’t exactly sure what a rip current was, all I knew was that it was obviously dangerous and it pulls you out into the ocean. So, I still went in the water because everyone else didn’t seem too worried about it. While I didn’t get pulled out into the ocean by the rip current, I did get a bad sting on my leg from a jellyfish (and it hurt!). Well, rip currents involve radiation stress, which is the force exerted on the water by the wave. Rip currents are powerful currents of water that narrowly run from the beach out into the ocean. They occur when there are variations in the patterns of the waves breaking, and large waves break closer to the shore. All of the water from the crashing wave wants to find the path of least resistance back to the ocean, causing the rip current. The force of the rip current depends on the height of the wave; the larger the wave, the greater the force of the wave, and the greater the force of the rip current. If you ever find yourself stuck in a rip current, don’t panic or swim straight back toward the beach like you would think. The force of you swimming in the opposite direction of the current is not large enough to get you to shore, the rip current has a much greater force. Instead, swim parallel to the shore until you get out of the current, or float out with it, and then once the current stops, swim diagonally back to the beach.
  12. Sledding Physics

    One of my favorite winter activities: SLEDDING! (although not the walking back up part). My house is backed up to the woods and a big hill, so when I was younger we would always go sledding (and try to dodge the trees), and make jumps to go off of on the way down. At the top of the hill, you have the most potential energy because you are at the greatest height. At the bottom of the hill, you have the most kinetic energy because you are moving the fastest and all the potential energy has turned into kinetic. Sledding only works when there is snow on the ground, if you try to go sledding on a grassy hill it won’t be as fun because snow helps to eliminate friction. Snow has a lower coefficient of friction than grass, so the force of friction will be smaller, and you will go down the hill faster. The normal force and gravity are the main forces during sledding, so the more you weigh, the greater the force will be and the faster you will sled down the hill. Also, the steeper the hill, the faster you will sled because with a greater angle there is a greater force. Sledding is much more fun when you’re going fast, so if you like having fun and moving fast, sled on snow or ice, increase your weight, and find a steep hill to go down!
  13. Christmas Physics

    Even though it is well past Christmas, I figured why not use physics to try to prove a myth that many kids believe, the myth of Santa and his reindeer. While Santa is said to have magical abilities that allow him to deliver presents in one night all over the world, let’s pretend that Santa doesn’t have magic and he just obeys the laws of physics. So, Santa has to visit around 500 million houses in the span of 31 hours (taking into consideration different time zones and the rotation of the Earth) and deliver at least one present to at least one child. This means that Santa has to visit about 4480 houses per second, or spend .0002 seconds at each house. In order to travel fast enough to make this trip in one night, Santa would have to travel at around 6500 mph, which is completely doable (in a rocket). Since Santa would be travelling this fast, he would definitely need some type of heat shield for himself and the reindeer to endure trillions of joules of heat, or else he would just be a flaming ball shooting through the sky. Now, what about all the cookies and milk? Well, these could *easily* be converted into energy to fuel his sleigh using the equation E=mc2. So, I guess Santa could be real, it’s just not very plausible. It’s much easier to just stick with the Santa has magical abilities thing! Check out this fascinating article that goes much more in-depth than I do (it uses different numbers than me as well): https://www.snopes.com/holidays/christmas/santa/physics.asp
  14. Sulfur Hexafluoride

    One of my younger brother’s favorite shows to watch is Mythbusters, and repeats are on almost every day. Well, a couple of days ago I saw a video about inhaling sulfur hexafluoride. Everyone has heard someone talk after inhaling helium from a balloon, they sound really funny because their voice is very high. The effect helium has on the voice is because it is much less dense than air. It causes the speed of the sound of your voice to increase, whereas the frequency of the vocal cords doesn’t change. Inhaling sulfur hexafluoride has the opposite effect of helium, it causes your voice to go extremely deep, like Darth Vader. This is because it is much denser than the air we breathe in, causing the speed of sound of your voice to decrease while the frequency stays the same. It is really entertaining and amusing to watch someone talk after inhaling sulfur hexafluoride!
  15. Let's Talk About Webassign

    An app would be much more convenient!

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