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Homework Help: Gravitational Force between three forces

  1. Nov 12, 2012 #1
    1. The problem statement, all variables and given/known data[/b]
    There's a 20kg ball and two 10kg balls 20cm above it. One of the 10kg balls is 5cm to the right of center and the other is 5cm to the left of center. What is the net gravitational force on the 20kg ball

    2. Relevant equations[/b]
    F=GMm/R2


    3. The attempt at a solution[/b]
    M=20kg, m=10kg, G=6.67E-11 and R=√(.202+.052)=.206m
    [itex]\Sigma[/itex]Fx=0; because the 10kg ball are equal distances away from the 20kg ball along the x-axis
    [itex]\Sigma[/itex]Fy=2*(((6.67*10-11*10*20)/(.2062))*(.2/.206))=6.1*10-7
    I know the answers supposed to be 3*10-7
     
  2. jcsd
  3. Nov 12, 2012 #2

    TSny

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    Your work looks correct to me.
     
  4. Nov 12, 2012 #3
    All right thanks I'm just going to assume the books wrong it wouldn't be the first time
     
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