Calculating Freeflight rocket accelleration

I have made a short snapz movie.

Although the movie was created at 30fps, EVN was running at 47fps. I do ot know how this will affect the calculations.

http://webserver.smp...c/AccelTest.mov

First, I fire a few 500-speed rocket, then a few 1000-speed rockets, then a 1500-speed and finally a 2000-speed rocket.

I need some help with how to caculate this, as I don't realy have a clue where to start.