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Comets #hashtag

Comets are pretty amazing. On Friday in ED512, we had a brief review of the physics of motion while examining graphic organizers. The amount of kinetic energy in an object is one half the mass times the square of the velocity. While watching the Science Channel this afternoon, I learned that a comet can travel up to 1,000,000 miles per hour and be miles across. So, I picked a three mile diameter comet, converted into SI units and did the math (assumed that the comet has the density of water-ish). The kinetic energy of the quickly moving comet that I just described would have a kinetic energy of 5.89E24 joules. It's 5,890,000,000,000,000,000,000,000 joules. That is a lot. It's about 1,000 times the energy contain in all the natural gas in the world (not all the natural gas used this year, but all the natural gas reserves currently waiting to be extracted).

That got me thinking about the weird comparisons that we make. If something is long, we say that is the length of X football fields. If it's really long, we say it is the length of Y Empire State Buildings, laid on their side. When it's astronomically long, it could wrap around the Earth X times or to the Moon Y times. The volume of something large is measured in multiples of Olympic swimming pools (or fill up a bunch of football stadiums). We use strange units of measurement.
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