IIRC, the range was 72m and the time of flight was 4.06s? So I used s = ut + 0.5at2, sub'ed in s = 72 and t = 4.06, then rearranged in terms of u, which turned out to be 17.734ms-1. The second part, I had no idea how to prove that it was the same rocket. (Was it even the same rocket? O.O; Did...