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Homework Help: The Moon And The Earth, Acceleration ( Question Answered, Just need check )

  1. Mar 25, 2010 #1
    The Moon And The Earth, Acceleration ( Question Answered, Just need check ) :D

    The question we were given was.:

    Given the facts that (i) the acceleration due to gravity at the surface of the Earth is 9.80 m/s2, (ii)
    the Moon orbits the Earth every 27.32 days, and (iii) the radius of the Earth is 6.38 × 106 m,
    estimate the distance, R, between the centre of the Earth and the centre of the Moon. (Hint:
    write down the relevant equations and rearrange them to give expressions for R. You will find
    that many of the variables cancel out).

    I have attempted it and this is my answer:
    2pi*R=T*v
    R=2pi/(T*v)
    a=v^2/R v=sqrt(aR)
    R*sqrt(R)=2pi/(T*sqrt(a)) (a=acceleration(9.8m/s2), v=velocity, T=period time(27.32 days))

    Is this the correct method, could anyone please tell me and clarify?
    And also, how do I get rid of the sqrt(R), is there anyway to give the expression just in terms of R?

    Any Help and Contribution will be greatly appreciated.
    :D
     
  2. jcsd
  3. Mar 25, 2010 #2

    kuruman

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    Gold Member

    Re: The Moon And The Earth, Acceleration ( Question Answered, Just need check ) :D

    Your approach is correct however the second equation does not follow from the first. Try again.
     
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