The distance from point A to point B is s. In the motion from A to B and back , the speed for the first part of the motion is v1 and the speed for the return part of the motion is v2. The avg speed for the entire motion is v. (1) prove that v=2v1v2/v1+v2. (2)Deduce that it is impossible to average twice the spèed of the first part of the motion, thats, its impossible to have v=2v1