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Edexcel A2 Physics Unit 5 'Physics from Creation to Collapse' watch

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    (Original post by JayAyy)
    Mass of the Earth 6x10^24. That was probably something I've always known :coma:
    But it didnt come exactly right?
    somewhere around 6. something?
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    (Original post by Bronze92)
    it was 1/4 for me
    thats wrong unfortunately.
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    what did people get for the energy of the alpha particles.....5.26Mev?
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    (Original post by Pegasus92)
    But it didnt come exactly right?
    somewhere around 6. something?
    I got something like 5.99somethingsomethingsomething, so I could only round it to 6.
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    (Original post by Zak979)
    what did people get for the energy of the alpha particles.....5.26Mev?
    yeah got that.
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    (Original post by JayAyy)
    I got something like 5.99somethingsomethingsomething, so I could only round it to 6.
    I remember getting some 6. something, but no problem.
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    I got 5.9 x 10^24..

    And was RMS 1/16 or 1/4??
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    1/16
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    Guys are you sure about the root mean squared question?

    Oxygen mass = 32, Hydrogen (I think it was hydrogen) = 2

    They wanted

     \frac {Root mean squared of oxygen molecule}{Root mean squared of hydrogen molecule}

     \frac {m<c^2>}{2} = \frac {3kT}{2}

     <c^2> = \frac {3kT}{m}

    3kT was the same for both

     c = (\frac {Constant}{m})^{1/2}

    For oxygen


     c = (\frac {Constant}{32})^{1/2}

     c = \frac {Constant}{32^{1/2}}

    For hydrogen

     c = \frac {Constant}{2^{1/2}}

    So

     \frac {Root mean squared of oxygen molecule}{Root mean squared of hydrogen molecule}

    Is

     \frac {\frac {Constant}{32^{1/2}}}{\frac {Constant}{2^{1/2}}}

     \frac {2^{1/2}}{32^{1/2}}

    = 1/4?
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    In the lungs question.. Were there 4 parts or 3?
    I remember the assumption, the mass per second, and the rate one at the end..
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    (Original post by Sasukekun)
    Guys are you sure about the root mean squared question?

    Oxygen mass = 32, Hydrogen (I think it was hydrogen) = 2

    They wanted

     \frac {Root mean squared of oxygen molecule}{Root mean squared of hydrogen molecule}

     \frac {m<c^2>}{2} = \frac {3kT}{2}

     <c^2> = \frac {3kT}{m}

    3kT was the same for both

     c = (\frac {Constant}{m})^{1/2}

    For oxygen


     c = (\frac {Constant}{32})^{1/2}

     c = \frac {Constant}{32^{1/2}}

    For hydrogen

     c = \frac {Constant}{2^{1/2}}

    So

     \frac {Root mean squared of oxygen molecule}{Root mean squared of hydrogen molecule}

    Is

     \frac {\frac {Constant}{32^{1/2}}}{\frac {Constant}{2^{1/2}}}

     \frac {2^{1/2}}{32^{1/2}}

    = 1/4?
    :yep:
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    what were the 2 assumptions
    temperature and mass right?
    for the lung question
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    (Original post by fredbraty)
    :yep:
    nooo
    Its 1/16, but I dnt remeber how to proof it.
    yadas proofed it though for you, didnt he.
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    (Original post by Pegasus92)
    nooo
    Its 1/16, but I dnt remeber how to proof it.
    yadas proofed it though for you, didnt he.
    no yadas put 1/4 as well.
    What he said is that it was easy for someone to confuse and put 1/16.
    You didnt see the "root" word.

    There were lots of tricks as i said previously.
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    (Original post by yadas)
    :yep:
    They asked for the mean speeds, not for the mean square speeds (which would be 1/16).
    That's what Yadas said^, he's saying it's not 1/16.
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    oh well its only one mark
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    (Original post by yadas)
    :yep:
    They asked for the mean speeds, not for the mean square speeds (which would be 1/16).
    so whats the answer for that?
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    (Original post by JayAyy)
    I got something like 5.99somethingsomethingsomething, so I could only round it to 6.
    what did you put for the 2 assumptions.
    lung question?
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    same mass of air, and constant temperature of air
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    I put assumptions: constant temperature and air behaves as an ideal gas..
 
 
 
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