Thanks for the post. By the way, I'm still struggling to find the answer for this question.
What I've done is first find the velocity of the particle in the laboratory frame,
a=\frac{c}{5} so v=\frac{ct'}{5}
Where t' is the time measured in the laboratory frame.
As dt'/dt=\gamma...
The question is:
A rocket has a constant acceleration in a rest frame that is 0 to 0.8c in 4s. What is its proper time?
This question I found, I guess I'll have to use integration but don't have a clue where to start off. Could you give me some ideas please?