A 5-kg motorbike moving at 10m/s to the left collides with 6-kg motorbike moving at 12m/s to the right. the two bikes stick together after they collide. find the final speed of the composite objects and the kinetic energy dissipated in the collision.
conserve momentum:
5(-10) + 6(12) = (5+6)v
That will give the final velocity v.
Then find KE (1/2 mv^2) for each body before and after the collision.