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Net gravitational force

  • #1
Objects with masses of 285 kg and a 585 kg are separated by 0.390 m. Find the net gravitational force exerted by these objects on a 30.0 kg object placed midway between them. Then, at what position (other than infinitely remote ones) can the 30.0 kg object be placed so as to experience a net force of zero?

I found the net gravitational force to be .000015798. The second part of the question is what I dont get. I tried F1-F2=0 and F2-F1=0 and setting them equal to each other so that

.000000451/(.39-x)^2 = .000001491/x^2

but it didn't come out right.
 

Answers and Replies

  • #2
Hootenanny
Staff Emeritus
Science Advisor
Gold Member
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6
Consider the force exerted on the third object by each of the two masses; set the distance from mass 1 to mass 3 as d;

[tex]F_{13}=F_{23} \Rightarrow \frac{Gm_{1}m_{3}}{d^{2}} = \frac{Gm_{2}m_{3}}{(0.390-d)^2}[/tex]

Does that make sense?
 

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