Combination of Velocities

The simple addition of velocities cannot be quite right at high speeds.  Let us consider two objects moving along the x axis with speed v>0.5c , going in the opposite direction of one another.  Looking at the speed of either object relative to the other one, we get a v'>c speed. Again, the right result is obtained with the help of the Lorentz transformations:

If the two objects are 'A' and 'B', the speed of object B is measured v'B by the observer sitting on object A.
You can see the solution to the 'Combination of Velocities' problem with two aircraft here.
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