Fun science challenge.

Discussion in 'The Lounge' started by ninja08hippie, Oct 9, 2012.

  1. ninja08hippie

    ninja08hippie Official SF Hugger
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    A skydiver is doing a jump from space (high altitude balloon.) There were a number of comments on the news article asking how he wasn't going to burn up in the atmosphere. He is actually higher than several early space missions, which did require heat shields, so my challenge is this: explain why Mercury Missions needed a heat shield, but the skydiver doesn't.

    I'll explain how it works fully in a day or so if no one can figure it out. No googling! It's actually pretty common sense, so you should be able to figure it out without having to google. If you do google out of curiosity, just admit defeat here and don't ruin the challenge for anyone else. If you know, post it and the games over.

    I'm curious to see how the well science is taught in school, probably learned this in fifth grade, or should have.
     
    #1 ninja08hippie, Oct 9, 2012
    Last edited: Oct 9, 2012
  2. mrcock

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    it can be out of several reasons

    he slows by something he has so he ain't accelerating

    he has a shield from something that covers him

    the angle of his trajectory is not straight, like not 90 degrees, but 45 or something

    did I just destroyed you?

    :lol
     
  3. ninja08hippie

    ninja08hippie Official SF Hugger
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  4. mrcock

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    wow

    gotta be something amazing and super simple, isn't it?

    :lol
     
  5. mrcock

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    I know, he would go down by a spiral. now I fucked you up, isn't it?

    :lol
     
  6. Meee

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    Here's my guess:

    He doesn't enter the atmosphere already going an orbiting speed.
     
  7. ninja08hippie

    ninja08hippie Official SF Hugger
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    Aww, that didn't take as long as I thought it would. Even my some of my fellow scientists at work didn't know that.


    Okay, detailed explanation. When jumping out of a balloon, he has a forward velocity of zero, and a maximum downwards velocity of about 700mph, not enough to create enough heat to burn up.

    Spacecraft don't have very high downward velocities either, but they have forward velocity of 17,500mph. It's that velocity which creates heat. In a fun side note, when a spacecraft comes out of orbit, it doesn't thrust down, that wouldn't work, they thrusters actually push them backwards, slowing them to fall into earth.
     
  8. mrcock

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    so you asked for the explanation why he wouldn't get burned, not how he avoids being burned?

    aahhhhh

    :lol
     
  9. Meee

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    I have three other questions, however:

    Won't his body create too much resistance to break the sound barrier? Aircraft that break the sound barrier have to be very pointy and so on.

    Also, as he approaches the sound barrier, won't there be very bad buffeting that could injure him? Early planes that tried it broke up.

    And finally, how will he stop gently enough? Won't opening a parachute at such a high speed make too much of a jerk with too many g forces?
     
  10. OverSinged

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    Make the lines to the parachute out of bungie cords :D

    No, he shouldn't break the sound barrier, he should be going at terminal velocity, which, now that I think about it, is one of the reason's he shouldn't have to worry. As the atmosphere thickens the terminal velocity drops and he should slow down.

    If I remember how terminal velocity works, that is.
     
  11. Meee

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    Well I just read around on the internet and apparently he would go at his highest speed when he was still very high and the air is very thin. Then he'd go into thicker air and actually slow down before it was time for his parachute to open.
     
  12. OverSinged

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    That's what I just said :D

    All about that Terminal Velocity.
     
  13. Meee

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    However, the terminal verlocity is higher in the thinner air, so I guess it's still possible that he could break the sound barrier. Also, there would be less buffeting and so on because the air is so thin. Breaking the sound barrier up there doesn't have as much impact.
     
  14. OverSinged

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    True, I still don't think you could break it without damaging something. Of course, my scientific knowledge is hazy in that department, so I'll leave it to the real scientists to tell him he's an idiot.
     
  15. Maverick

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    I want to do it, is all I know. :)

    Free fall for 25 minutes, open chute at 2000 feet, I think is what I read 2 days ago.
     
  16. Maverick

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  17. lbushwalker

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    Meee,
    Some things in life are just not equal.
    You are not only young, refined, gorgeous, witty and now prove to possess superior intellect!
     
  18. ninja08hippie

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    It is likely that he will break the sound barrier actually. Planes have trouble because they do it at very low altitude (comparatively) so they have a lot more air vibrating around them. Because he is starting at 120,000 feet, there is no atmosphere, so his terminal velocity is much much higher, it also means that the speed of sound is much much lower. The speed of sound is dependent on the density of the air, it's not a set velocity ;) Remember, in space, you still weigh and accelerate (almost) the same as you would on the ground, it's orbit that makes astronauts seem weightless.

    As he descends into the atmosphere, his terminal velocity will decrease, so we will actually decelerate as he nears the earth, at a slow enough pace that it won't injure him. He will deploy his parachute at normal deploy altitude, at which point he will be going no faster than a normal skydiver :)
     
    #18 ninja08hippie, Oct 10, 2012
    Last edited: Oct 10, 2012
  19. CosmicEye

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    You have to remember that terminal velocity is 9.8 m/s (~32.1 ft/sec or ~120mph) in the Earth's atmosphere from resistance of the air. Since he is above the atmosphere he will travel faster than terminal velocity and slow down as he enters, but not fast enough to cause a fire. I think he will get alittle warm but he wont be traveling at thousands of mph like meteorites do.

    I remember watching the vid of the first guy that jumped from the beginnings space. I think it was 19.X miles but this guy will be at 23 miles (I think), so slightly higher. Today on the radio they were saying that he will risk his blood boiling. I cant imagine that