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Math Help - confussion on changing measurements etc

  1. #1
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    confussion on changing measurements etc

    So I'm working out the volume and have 0.5mm, 10km & 100km.

    I've changed 0.5mm into 5.0x10^-6 km

    So it works out as 5.0x10^-6 km x 10km x 100km = 5.0x10^-4 km^3

    I also need to work out mass using the desity value of 1x10^3 kg m^-3 but do I need to convert any value like I did with the 0.5mm and what would the measurement be in? kg m^-3 x km^3 becomes what?
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  2. #2
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    Hi dg2008

    0.5 mm is not 5.0x10^-6 km

    0.5 mm = 5 x 10^{-1} mm = 5 x 10^{-1} \;mm * \frac{1 \;km}{10^{6}mm} = ...km


    As for the density:

    1x10^3 kg m^{-3}=1x10^3\frac{kg}{m^3}*\frac{1 m^3}{....km^3} = ....\frac{kg}{km^3}
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  3. #3
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    my mistake I have writen 5x10^-7 down but on here typed it wrong. Prob' worng also.

    Density I just don't get at all.
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  4. #4
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    Hi dg2008

    1 m^3 = .... km^3

    Can you figure it out ?
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  5. #5
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    1 m^3 = 0.001 km^3 or 1x10^-3



    So then the m^3 & 1m^3 cancel each other out. Thats about as far as I can go lol Is it just 1x10^3 x 1x10^-3?
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  6. #6
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    Hi dg2008

    Nope. 1 m^3 is not 0.001 km^3

    1 m^3 = 1 m * 1 m * 1 m = 0.001 km * 0.001 km * 0.001 km = ....

    Then you put the number in the "..." and you're right that the two m^3 will cancel out each other.
    Last edited by songoku; September 10th 2009 at 07:44 AM.
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  7. #7
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    1.0 10^-9 km^3
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  8. #8
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    Quote Originally Posted by dg2008 View Post
    1.0 10^-9 km^3
    Yes, that's right

    Quote Originally Posted by songoku View Post
    Then you put the number in the "..." and you're right that the two m^3 will cancel out each other.
    Have you tried it ?
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  9. #9
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    So I put 1.0 10^-9 km^3 into the first ... then does it become

    1x10^3 kg x 110^-9 km^3 as the m^3 has be canceled out.

    or

    1x10^3 kg / 110^-9 km^3
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  10. #10
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    Hi dg2008

    Judging from the equation I wrote, which one is right? km^3 should be at numerator or denominator?
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  11. #11
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    I think it's the / not x one I wrote.

    Do you know anywhere online where I can write equations correctly?
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  12. #12
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    You're right. It's the "/" one

    I think you can learn how to write equation here : http://www.mathhelpforum.com/math-he...-tutorial.html
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  13. #13
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    yay so:

    1x10^3 / 1x10^-9 = 1x10^12 kg km^-3 ?
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  14. #14
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    Yups
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  15. #15
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    so I have 5.0x10^-4 km^3 as the volume and 1x10^12 kg km^-3 as density but how is mass worked out?

    I know its m= d x v but what do I do about the measurements do the km^-3 and km^3 cancel out?
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