1. The problem statement, all variables and given/known data Derive from Newton II the thrust (the force produced by the rocket exhaust) achieved by a rocket motor which ejects material with constant velocity u and mass ejection rate a. 2. Relevant equations 3. The attempt at a solution Not sure...I know how to derive vf = vi + u ln(mi/mf) but thats not what its asking for.. So my attempt F = mdv/dt then using what we have for m i come to F = a(vf-vi)/ln(M/m-at) is this right?