1. The problem statement, all variables and given/known data Two stars move in circular orbits about one another with period T due to their mutual gravitational attraction. If the objects are suddenly stopped, show that they will then collide with one another after a time T /(4√2) 2. Relevant equations T = ∫dt dA/dt = (1/2)r2d∅/dt Fg= -Gm1m2/r2 3. The attempt at a solution So I believe I've determined the period in terms of radius. Simply by substituting what dt equals into the integral and solving. You get T = 2piμr2/4l, where l is the magnitude of the angular momentum, and μ is the reduced mass. After this I'm a little stuck. I've tried integrating the acceleration given by the force on each star, but I get stuck with the differential equation dv = -Gm1/(4r2). Maybe this is the totally wrong way to approach it. In that equation r is not a constant, therefore you can't just integrate it. If doing it this way, you'd have to replace r with a constant multiplied by something having to do with time, but I don't know what that would be. And also, regular kinematic equations can't be used of course since this is not constant acceleration. Thanks in advance!