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running_dry
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In December of 2013 the European Space Agency launched Gaia, the most accurate telescope to ever be put into space. Its 1 gigapixel camera (that's 1 billion pixels or 1000 megapixels) is said to be able to measure a human thumbnail from the moon or detect the width a human hair from a distance of 1000 Km, which is some pretty incredible imaging science right there. Whats more, telescopes work better where its dark, so the ESA is putting it in orbit around the sun, around the L2 lagrange point which is out past the moon- which sounds funky but let me explain. L2 is 1500000 Km from the Earth in the direction away from the sun, and from there Gaia will orbit the sun with the same period as the Earth, but free of much of the Earth's light and gravity. Rather than staying still at the L2 point however, ESA is using advanced flight dynamics to put Gaia into a 3 dimensional pendulum-like orbit about L2. [below are visuals of the L2 lagrange point and Gaia's motion around it] The period of Gaia's motion around L2 is going to be about a year an a half. From its orbit around L2, Gaia will operate for at least 5 years creating a very accurate map of over a billion stars, a million quasars and search for exoplanets. The images produced by NASA's hubble telescope are stunning, but with much superior imaging technology and being a million kilometers farther from earth than the Hubble, I can't wait to see what Gaia sends back. -
This is the followup to my last post about climbing Giant Mountain. You may have notice that I only talked about the energy I expended climbing the mountain. If you're thinking "Couldn't he have just doubled the energy going up to get total energy", you're wrong and need to: 1) read this 2) stop acting like you know me. The main problem was that, as I mentioned in the last post, the trail became increasingly snowy and icy as we neared the summit. Actually it was like starting in New York in October, climbing through NY in December and then ending up in Alaska at the summit. That wasn't so bad on the way up but the way down it turned into a deathtrap. Every bare rock surface was covered in black ice and everything else was blanketed in slush. The key to surviving the descent (not an exaggeration) was to first of all lower your center of gravity. By crouching down or even sitting and sliding there is a much lesser chance of falling because having more mass closer to the ground means better traction and control in the event of a fall. We got down most of the top half of the mountain by sliding on our butts, so the key to that was to align yourself with where you wanted to go. In a low friction environment its difficult to change the direction of ones momentum because the low coefficient of friction means that inertia altering forces are hard to apply since hands and feet just slip. So If one starts an intentional slide in the direction of a cliff and there's nothing to grab onto, guess where that someone is going to end up? The rick (to not dying) is to slide towards trees or roots or large rocks and not get going to fast so you have time to stop yourself. In the end we all made it down relativity injury free (although I did take a few hard falls), but I just wish someone had given me the forecast of "snow, ice, wind and high chance of death."
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I would like to take a step back from physics to propose another law on the effects of procrastination on the APlusPhysics blogs. I have already explored the relationships between amount of procrastination and both quality of blog posts and hours slept the night they are due. Every time I refresh the "dashboard" page five new posts pop up, and I have noticed that the same posts don't stay on the front page for very long. It would seem that we are all hurting ourselves in terms of views by all waiting until the last possible second to do these because in the time that it takes to write the next post, your last post has already disappeared, never to be seen again by anybody. On the other hand increased site traffic might expose your blog to more potential readers. All of this of course really only matters if you care about how many people read your posts (I do, just because I take the time to write them). I could also be mistaken about how the dashboard works....
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There's one thing that has always bugged me about the sport of cross country: the proximity of the start line to the finish line. Nine times out of ten I would estimate that the positions at which I start and finish a 5000 meter race are within 400 meters of one another. Now obviosly i understand that its a 5k race, not a 400, but it makes me seem very slow. With my (rather quick) personal best time of 15 minutes, 21 seconds (921 seconds) my average velocity (speed=distance/time) over a 5km distance is a respectable 5.42 m/s. However my actual velocity (dispacement/time, estimated that the start is 400 meters from the finish) is an abysmal 0.43 m/s. Every course has "tangents"- lines that can be run on the course that can cut off like 50 meters from 5000 but unfortunately theres nothing legal that can be done to cut off 4600. On the plus side I can say that I won a race with a velocity of .96 mph.
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So the other day I was skiing along on one of those straight, flat trails so I was naturally a little bit bored. So I decided to see how high I could jump. I pushed off the ground pretty hard and... got like 2 inches of air. I was pretty disappointed in myself so I tried again. This time a squatted down and pushed off the ground with as much force as my skinny legs could muster and... 2.5 inches. Whats wrong with me? So I stopped and tried to jump vertically while not moving and I got much higher (although it was still pretty embargoing). I stood there for a minute and tried to figure out what was going on. Why can I jump higher while standing still than while moving? Eventually I hypothesized that while standing still the vector of the downward force created to make the jump is directed normal to the ground, maximizing the reaction from the ground; however if you try to jump while sliding across the snow on your skis some of the force is applied parallel to the ground due to your forward motion, in effect creating the same magnitude of the resultant force vector but at an angle which trades some vertical height for horizontal distance. Or maybe I'm just really bad at jumping...
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