# Reaching the speed of light, rockets [duplicate]

Well I've been wondering quite a long time about this problem. If you had let's say 10 rockets, each of them having a length enough to provide space for an acceleration of another rocket inside. Each rocket would accelerate from 0, to 1/10 of speed of light. From the observers point of view, wouldn't the last rocket achieve the speed of light (since the speeds add up).

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## marked as duplicate by Qmechanic♦, dmckee♦Sep 21 '12 at 20:43

This question was marked as an exact duplicate of an existing question.

I know that you need infinite energy to accelerate an object of a certain mass to the speed of light, but the rockets, are not even approaching the speed, so that doesn't work here. – Bartlomiej Lewandowski Sep 21 '12 at 20:36
so what you are saying, that comparing the speeds of rocket 9,10 ,their speed difference would be much smaller than 1/10 of the speed of light, but from the rocket nr 10 point of view, the difference would be exactly 1/10 speed of light – Bartlomiej Lewandowski Sep 21 '12 at 20:42