1. The problem statement, all variables and given/known data Three uniform spheres are fixed at positions shown in the figure. i) What is the magnitude of the force on a 0.0150-kg particle placed at P? ii) What is the direction of this force? iii) 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? 2. Relevant equations Fg = -GMm/r2 3. The attempt at a solution I think I've got the answers for part i) F = 9.67×10-12 N ii) 45°. I got i) by simply working out the force due to gravity on P due to each of the spheres and then resolving them to see the component of the force along the 45° angle. However part iii) i'm struggling with. Obviously the force will increase as P gets closer to the origin. This will mean that the acceleration will increase. I think Fg ∝ 1/r2 and the acceleration a = Fg/m. Because the acceleration is non constant I think I have to integrate a with respect to t to find v. However there is no mention of t anywhere in this question! From here I'm not quite sure where to go and any help would be greatly appreciated!