# Gravity and mass of two objects

## Homework Statement

There are two masses of unknown weight on a straight line with a small red particle between them. At x (Measured from the center of m1) = .515 the particle does not move. What is the ratio of the two masses? i.e. m2/m1.

## The Attempt at a Solution

So do I use F = G*m1*m2/r^2? Since the particle isn't moving then the forces are balanced does this mean F = 0 then?

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tiny-tim
Homework Helper
Hi AnkhUNC! So do I use F = G*m1*m2/r^2?
Not exactly … you use F1 = G*m*m1/r1^2 and F2 = G*m*m2/r2^2 and F1 = F2.

Hint: what is the relationship between m1/m2 and r1/r2? On the right side the min x = .043 on the left side the max is .957. It starts out at .5 though which is in the middle so I guess <- is 0 and -> is 1.

r1/r2 = 1, they're both .5 away so .5/.5 = 1.

m2 is greater than m1 because the attraction is stronger so does m2 = .515 and m1 = .485?

So F = G*m*m1*m2?

tiny-tim
Sorry, AnkhUNC, but I honestly have no idea what this means.  Hint: divide F1 by F2. 