Homework Help: Question on forces and ratios

1. Sep 18, 2008

Nivlac2425

1. The problem statement, all variables and given/known data

Here's the question:
Two forces, Fa and Fb, are applied to an object. The larger force is Fa. When both forces point due east, the object's acceleration has a magnitude of 0.50 m/s^2. However, when Fa points due east, and Fb points due west, the acceleration has a magnitude of 0.40 m/s^2. Find the ratio of Fa/Fb of the magnitudes of the forces.

2. Relevant equations

F = ma ?
d = Vt + 1/2at^2 ?

3. The attempt at a solution

I've tried manipulating the F = ma equation to no avail. Maybe it has something to do with d = Vt + 1/2at^2 but I think maybe I'd have to use Fa + Fb = sigmaF.
But to be honest, I have no idea where to start, especially with finding ratios. I just need a little help forward. Thanks

2. Sep 18, 2008

rl.bhat

Fa + Fb = ma1........(1)
Fa - Fb = ma2.........(2)
take the ratio of 1 and 2 and solve for Fa and Fb

3. Sep 19, 2008

Nivlac2425

I've tried something like that, but the book says that the answer is 9. Does that change anything?

4. Sep 19, 2008

Nivlac2425

Nevermind my last post, I've gotten the answer to be 9. Thanks! I'll know how to do ratios now