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Mathematics qs

  1. Nov 29, 2008 #1
    I was doing the equation of E=mc^2

    So its like this:

    If M = 1kg and C=300 million m/s,

    Then E= 1 x 300 million x 300 million = 90 000 million joules/90 billion joules

    But the qs is,

    If I convert c to 0.3 billion m/s,

    then E = 1 x 0.3 billion x 0.3 billion = 0.09 billion joules

    Why are both different? Can anyone explain the error?

    Thanks (:
     
    Last edited: Nov 29, 2008
  2. jcsd
  3. Nov 29, 2008 #2

    Vid

    User Avatar

    Neither of these answers are right. (3*10^8)^2 = 9*10^16
     
  4. Nov 29, 2008 #3

    CompuChip

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    300 million x 300 million = [itex](300 \times 10^6) \times (300 \times 10^6) = (300^2) \times 10^{12} = (9 \times 10^4) \times 10^{12} = 9 \times 10^{15}[/itex]
    while
    0.3 billion x 0.3 billion = [itex](0.3 \times 10^9) \times (0.3 \times 10^9) = (0.3^2) \times 10^{18} = (9 \times 10^{-2}) \times 10^{18}) = 9 \times 10^{15}[/itex].

    I think your problem is that you are writing
    300 million x 300 million = 90000 million
    while it is actually
    90000 million million.

    Scientific notation is handy! :)
     
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