Two astronauts float in space, at rest relative to each other. The first astronaut, mass M1 = 66.2 kg, holds a ball of mass m = 8.39 kg, which she throws at speed v = 7.64 m/s. The second astronaut, mass M2 = 94.0 kg, then catches the ball. Find vrel, the speed one astronaut is moving relative to the other after one throw and one catch.