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About elementcollector1

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  • Favorite Area of Science
    Inorganic Chemistry
  1. I recently read about an interesting and potentially relevant housing development: Installing packets of paraffin wax in the walls. These absorb the heat during the day, and release it at night, lowering the change of temperature in rooms. Found here: http://www.wpi.edu/Images/CMS/News/Apelian_JOM.pdf
  2. Sn's valency is 4, not 6 - the Na+ ions take care of the rest. As for separation, I would suggest mixing with an acid to change the pH - hydrous Sn(OH)2 or Sn(OH)4 (can't remember which) should precipitate in a certain pH range.
  3. Not sure what you mean, Enthalpy - I've been doing calculations this whole time. Anyway, if there's no way to "cheat" the work equation (W = Fd) into thinking there's more distance than there really is, I think I'll have to settle for a system with a lower tolerance for falls - better than what a human could manage, but not perfect.
  4. Hmm. But shouldn't the plane be heavy enough that the reduced vertical momentum (from the action of the wings) is still greater than the vertical momentum of a person at terminal velocity? Source: http://www.avweb.com/news/savvyaviator/192153-1.html?redirected=1 3g might not be much acceleration, but considering the plane that's a whole lot of force. Then again, if deceleration's the issue, wouldn't there still be a problem even if all the force of landing was absorbed? Back to your earlier calculations on deceleration, the minimum distance to get the deceleration within "safe" (relatively speaking) limits would be 12 m. Is there any way to make this length less - as in, could it be coiled up or otherwise rendered shorter while still acting as if it were the full length?
  5. I don't get it - if the strut can stop an airplane, why wouldn't it stop a human (ignoring practicality)?
  6. Well, unless time travel is involved, I don't think I'll be applying the second method. After some thought, I wondered why we could survive airplanes landing (after all, that's quite some momentum!), and looked it up - apparently something called an 'oleo strut' absorbs most of the shock, apparently by damping with compressed air or nitrogen and oil. Hypothetically, what if a human pogo-sticked one of these off of a 1200-meter cliff (or some similar setup where the strut would take the brunt of the impact), in keeping with the earlier numbers - would they still be injured from deceleration? I would think they wouldn't if a few of these things could stop the vertical momentum of a passenger plane, but maybe I'm missing something more subtle.
  7. So if the acceleration is directly proportional to the stopping distance, what is the upper limit on deceleration for a human? Also, would it be possible to 'transfer' the acceleration somewhere else - as in, direct the shock somewhere it can be less harmful? Not sure on how shock 'moves', at any rate.
  8. So why is an airbag able to decelerate a person safely? After all, it's not all that big compared to a person, yet it stops collisions very well and allows the driver to survive mostly intact.
  9. What would be an appropriate "soft" substance? Foam, or maybe a type of rubber?
  10. Huh. So energy and shock absorption do nothing in this case, because the deceleration itself is enough to damage the human body?
  11. Okay, so assuming two pads, one on each of the person's feet, the contact area for the body would be about 20 cm by 10 cm, or 200 cm2. How would the force exerted on this area be calculated, then?
  12. It's mentioned on the webpage (http://www.sorbothane.com/) that it can be used for both "shock" and vibration applications.
  13. I've recently been considering buying a material titled "sorbothane", a very soft and energy-absorbent derivative of polyurethane. The product list can be found here: http://www.sorbothane.com/blog/wp-content/uploads/2012/12/11-26-12-Sorbothane_SPG_11.2012_v4.pdf My question is, when one examines the 4"-by-4"-by-1/2" square pad of durometer 70(product 0204025-70-10), it claims to be able to withstand a load of up to 7400 pounds, or about 33 kN. Now, this already seems kind of ridiculous, but maybe that's just how good it is. Maybe. But how does that translate to impact force? I've been trying to calculate, as a rough example, how much force a person would experience if they dropped from freefall at terminal velocity and hit the ground with one of these pads on each of their shoes. However, calculating impulse seems to be useless, as the amount of time the person takes to hit the ground is essentially zero. Attempting to derive from I = delta(p) where p is momentum, I arrived at something like 1600 kg*m/s impulse given a person who weighs approximately 600 N, but I don't know if that's correct, or even what to do with it if it is. Not only that, wouldn't the person experience some sort of force based on all the potential energy - turned - kinetic energy from the distance they fell?
  14. Is there any way to create a focused beam of sound - either a flat wave or a phaser - with a simple setup?
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