Relative speed between the two rockets?

Question

A person on earth notices a rocket approaching from the right at a speed of 0.78c and another rocket approaching from the left at 0.60c. What is the relative speed between the two rockets, as measured by a passenger on one of them?

Answer 1

1.38c. If someone's is on the rocket and looks at an object at rest, then it would seem to him as if the object was coming towards him at the speed he's moving in, if the object was moving like the other rocket, then it would approach faster so you add its speed. If you want to know more look up "relative velocity". Hope this helps good luck!  

Answer 2

This is a tough question. Relativity says that if their motion is constant, the passengers on either rocket could say that their rocket is not moving, and the other is moving past them at a certain velocity. Thus the first rocket would see the other coming at .60c, and the other would see the other rocket coming at .78c.

Newton would probably say that the two velocities, represented as vectors moving in opposite directions, that the slower rocket would see the faster one coming at .78c-.60c=.18c

Answer 3

In relativity, the frame of each of the rockets has a different clock rate and distance measure, and the notion of simultaneity in the direction of motion is altered, so the addition law for velocities is changed and can also be called the composition law for velocities. For collinear motions, the velocity of one rocket wrt the passenger on another rocket is given by: S=(U+V)/(1+(V/c)(U/c)) = (.60+.78)c/(1+.6*.78) = .94c.

Nothing goes faster then c, and doesn't even appear so!