1.To an observer two bodies of equal rest mass collide with velocities of 0.8c in different directions and cohere to produce a stationary composite body, to a second observer body A is at rest before the collision. a. Find the velocity of body B as measured by the second observer before the collision. b.What is the velocity of the composite body as measured by the second oberver? 3. my answer to part a: -1.6c/1+0.64 =-0.98c for part b. Could somebody please show me how to do this type of question? I am really stuck on this part .