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Homework Help: Gravitational fields

  1. Oct 2, 2011 #1
    1. The problem statement, all variables and given/known data
    It can be assumed that the Earth, to a good approximation, moves in a circular orbit about the sun. Determine the speed of the Earth.

    2. Relevant equations
    v2 = GMearth/r

    3. The attempt at a solution
    mearth= 5.98x1024
    R of earths orbit= 1.49x1011
    G= 6.67x10-11

    v2= (6.67x10-11)(5.98x1024)/ (1.49x1011)
    v2= (3.98x1014) / (1.49x1011)
    v= [itex]\sqrt{}2676.9[/itex]
    v= 51.7m/s

    Now here's the problem. My teacher said that the answer to this question is 2.97x104m/s
    What is it that I am doing wrong? D:
  2. jcsd
  3. Oct 2, 2011 #2


    User Avatar

    Staff: Mentor

    The important mass, the one that the Earth orbits, is the mass of the Sun.
  4. Oct 2, 2011 #3
    Ohhhh. Okay, I got it. Thank you
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