Question

Two manned satellites approaching one another at a relative speed of 0.200 m/s intend to dock. The first has a mass of 2.00 multiplied by 103 kg, and the second a mass of 7.50 multiplied by 103 kg. If the two satellites collide elastically rather than dock, what is their final relative velocity? Adopt the reference frame in which the second satellite is initially at rest and assume that the positive direction is directed from the second satellite towards the first satellite.