1. The problem statement, all variables and given/known data Two neutron stars are separated by a distance of 4.80 E 10 m. They each have a mass of 3.60 E 30 kg and a radius of 1.30 E 5 m. If they are initially at rest... How fast is each star moving when their separation has decreased to half its initial value? How fast is each star moving just before they collide? 2. Relevant equations (G = Newton's Gravitational Constant (around 6.67*10^-11) GPE = -G(m1)(m2)/r Work = GravitationalForce*Distance = GPE GravitationalForce = (G)(M1)(M2)/R^2 3. The attempt at a solution Both forces from each planet are acting on each other, so I put the total gravitational force as double the equation. Multiplied by the given distance to get work/GPE, and then took that and subtracted the same equation, except with the distance halved. Don't really know where to go from here.