Solving for Velocity of Particle in Deep Outer Space

[Ryanu]

Homework Statement

Three uniform spheres are fixed at positions shown in the figure
If the spheres are in deep outer space and a 0.0150-kg particle is released from rest 300 m from the origin along a line 45∘ below the -x-axis, what will the particle's speed be when it reaches the origin?

Homework Equations

The Attempt at a Solution

I calculated the Force on a .015 kg of a particle placed at P
I also knew the force would be at 45 degrees.
I don't know how to find the velocity of the particle if it's released 300m from the origin.

 

[gneill]

Think conservation of energy.