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Drinking a coke

  1. Jan 9, 2007 #1
    When I drink a coke with a straw would it be easier on Earth or on the moon? How is the atmospheric pressure involved here? Could you explain the process? Thanks in advance.
     
  2. jcsd
  3. Jan 9, 2007 #2

    Doc Al

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    What do you think?
     
  4. Jan 9, 2007 #3
    on the moon becuase the moon has less mass. Its not that difficult to figure out
     
  5. Jan 9, 2007 #4

    DaveC426913

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    Sounds like homework. What are your thoughts?

    [ EDIT ]Geez. I blinked...
     
  6. Jan 9, 2007 #5
    I would say even that it would be impossible on the moon, since there is no atmosphere, thus no pressure, so the coke cannot ascend through the straw. Is it correct?
    Why is it possible on Earth? When one sucks the air of the straw, why does the coke ascend, what is the origin of that upward force?
     
  7. Jan 9, 2007 #6

    It would be easier on the moon asuming you were in a capsle where there was air you could breath. The reason coke comes up a straw when you suck is you are taking out air. This makes a low pressure and the coke tries to fill in the low pressure by going up the straw.
     
  8. Jan 9, 2007 #7

    Doc Al

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    Sounds good to me.
    Reread your first sentence above! I think you almost have it.
     
  9. Jan 9, 2007 #8
    But in the Earth situation, I suck through the straw and take out the air that is above and exerting a pressure, on the surface of the coke, that is inside the straw. So is it the particles that are below the ones at the surface that exert pressure on them, thus an upward force that makes them to ascend through the straw. Is it correct?
     
  10. Jan 9, 2007 #9

    Doc Al

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    I think you've got it. Here's how I'd put it: You don't really "suck" the soda up the straw, it's air pressure that pushes it up.
     
  11. Jan 9, 2007 #10
    Is it the air pressure or the pressure of the other soda particles? The air pressure is downward, I think, so it cannot provide an upward force.
     
  12. Jan 9, 2007 #11

    Doc Al

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    The air pressure is transmitted to the soda. (Consider Pascal's principle.)
     
  13. Jan 9, 2007 #12
    Would you mind explaining it more detailed? Please.
     
  14. Jan 9, 2007 #13

    LeonhardEuler

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    It seems like we're neglecting the fact that without an atmosphere, the coke would boil away and there wouldn't be anything left to suck up. But maybe that's what the question intended.
     
  15. Jan 9, 2007 #14
    The question is from me to me, and I had not that intention :). Let's forget, that preciosity. But would it really boil at zero pressure and at the temperature of the moon?
     
  16. Jan 9, 2007 #15

    LeonhardEuler

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    A liquid boils when its vapor pressure is equal to the external pressure. The pressure of the atmoshpere at sea level is typycally about 760mmHg. At 70 °F, the vapor pressure of water is about 20mmHg, so if the outside pressure is less than this, it will boil. The temperature on the moon varies a lot since it doesn't have an atmoshere. Just googling it I get 107°C durring the day and -153°C at night.
     
  17. Jan 9, 2007 #16

    russ_watters

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    Pressure at a point is the same in all directions. It doesn't just push down, it pushes up, left, right, etc. If it didn't, water wouldn't flow because there would be no force pushing it sideways.
     
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