Two stars A and B very far from each other crash into one another along a straight line. The radius and masses of A and B are rA=7x10^8m, rB=9x10^8m; mA=10^30kg, mB=2x10^30kg. What are the velocities of A and B when they collide? Both stars staring @ rest
I use conservation of energy and momentum. Since they are very far apart and starting @ rest: Ki + Ugi = 0
=> 0 = Kaf + Kbf + Ugaf + Ugbf
the momentum part is vA2 =-2vB2
I got vB2 = 11.8m/s
i think this is wrong since the value is too small!