Following scenario: A rocket measuring 10 lightseconds in length accelerates near instantaneously to v=0.4c. Pre-acceleration two clocks placed at the endpoints of the rocket were synced. What will be the time difference between the two clocks post acceleration? I tried to figure it out, using two x-t diagrams, drawing the worldlines of the rocket's endpoints (green lines) as i would imagine them. Considering the innacuracy of the drawing, my rough estimate is that the time difference will be slightly over 4 seconds. Did i get it right? Here are the x-t diagrams edit: Also, is the time difference between the two clocks post acceleration decided only by the final velocity or does the "type" of acceleration (faster/slower) matter?