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Homework Help: Please help me calculate weight of a person on the moon

  1. Feb 3, 2010 #1
    the mass of the moon is about 7.5*10^22 kg and its diameter is about 3.5*10^6 meters. calculate the weight of a 70 kg person on the moon.

    so we got F=G*m1*m2/d^2

    G=6.67*10^-11N*m^2/kg^2

    to find the mass we can use m1= F*d^2/m2*G (how did we manipulate the first formula to get this? no matter how i try to change the first formula it never ends up like this one)

    i have been trying to solve this for a week now. it`s not a homework. i am just trying to teach myself physics and this book i purchased is very superficial and leaves huge holes in explanations.

    please show me how to solve this. including the manipulations with scientific notation.
    thanks.
     
  2. jcsd
  3. Feb 3, 2010 #2

    rock.freak667

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    you don't need to find the mass, the force F will give you the person's weight.
     
  4. Feb 3, 2010 #3
    so i have to use the first formula?

    and i`d like to know how exactly the second formula for m1 was obtained from the first one.
     
  5. Feb 3, 2010 #4

    rock.freak667

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    Yes.

    [tex]F=\frac{GM_1M_2}{d^2}[/tex]

    multiply both sides by d2 and then divide by GM2
     
  6. Feb 17, 2010 #5
    sorry for a reply long overdue. THANK YOU TONS, especially for breaking down the process of obtaining a formula from another.
     
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