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etracey99

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  1. etracey99

    Aurora Borealis

    By etracey99,

    Many of us know the Aurora Borealis as the 'Northern Lights'. This natural phenomenon is, of course, thanks to the physics of our Earth and its atmosphere!
    (Photo credit: NASA)
    The Aurora Borealis is an extremely beautiful event that occurs most often close to the magnetic poles of Earth. It occurs due to charged particles coming from the Sun of which collide with other molecules found in the Earth's atmosphere. Solar winds from the Sun carry these charged particles and when the wind passes by Earth, particles may be trapped in the atmosphere from the Earth's magnetic fields! The charged particles ionize molecules in the atmosphere, which give off light. This creates the Aurora Borealis!
    I had previously thought that the Northern Lights were from light reflecting somehow, but it awesome to see that it is caused by magnetism, which fits into our past few units very nicely.
  2. etracey99
    Today, the internal combustion engine is a very important part of the average person's life. We experience the wonder of this engine in most automobiles that use gasoline as a fuel. As one could guess, the Internal Combustion Engine is an engine in which combustion occurs internally... just kidding! (oversimplification at its finest). In all seriousness, let us discuss the four-stroke internal combustion engine since it is not too difficult to understand!
    It is called a four-stroke engine because there are four 'strokes' per combustion cycle (up, down, up, down). It goes like this:
    The first stroke is for the intake. The intake valve opens as the piston goes into its down position and lets in an oxygen-gasoline mixture (known as the fuel-air mixture). Going back to another post I wrote, the fuel-air mixture can be tuned for better gas mileage and/or power!
    The second stroke is to compress the fuel-air mixture in the combustion chamber. While the piston is on its way up, the intake valve quickly shuts and an airtight situation is created, which allows for the compression.
    The third stroke, or the combustion stroke, occurs directly as the piston is reaching the top of the chamber. The fuel-air mixture, in its extremely compressed state, is extremely flammable and when the spark plug goes off, explodes! This creates a great force and shoots the piston down.
    The fourth and final stroke is to push the exhaust out. As the piston is on its way back up, the exhaust valve is opened, and the air that is created after the explosion is let out so fresh air can be let in.
    After this, the cycle repeats itself! I found a diagram from keveney.com that I believe will help to imagine what it all means:

    This process is the origin of how your car actually moves! The combustion pushes the pistons, which turn the crankshaft, which turns gears in the transmission, which turns the drive shaft, which turns the differential, which turns the axles which turns your wheels! A lot of steps, but very useful to know!
     
  3. etracey99
    We live in a world where we are constantly trying to better our technology to be greater and more efficient. What if I told you that we achieved the most efficient mode of transportation of all time already? And what if I told you that this transportation was developed as far back as 1817? Behold! The bicycle.
    Since the first bicycle coming from Germany in 1817 (called the running machine), there have been great advancements in bicycles:

    Although this invention has been around for about 200 years, the bicycle proves to be one of the greatest and most efficient inventions in transportation. This is simply because bicycles are able to convert 90% of the energy that a human can put into it by pedaling directly into kinetic energy that powers you along. This is over 4x better than the conventional gasoline engine we use in most cars, which clocks in at only being 20% efficient with its fuel.
    In other words, if people could somehow use gasoline as energy in their bodies and ride a bike, it would be a 4x more efficient use of the same amount of gasoline when used in a normal automobile.
    So keep that in mind next time you want to go out to get ice cream or visit your friend down the road, a bike is a more efficient machine and it is environmentally friendly!
     
     
       

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