1. The problem statement, all variables and given/known data 2. Relevant equations conservation of momentum Thrust of rocket engine = -u (dm/dt) u is the velocity of the gas being expelled Also found this from Wikipedia, not sure if it is relevant 3. The attempt at a solution For these kinds of problems I assume you need to apply conservation of momentum on infinitesimally small parts. dp = (v+dv)(m-dm) + dm)(v-u) - mv + at the end of this equation how do I factor in the intake? I know dm will be the amount of fuel + air it shoots out back and If this is the wrong approach and I supposed to use the equation form wiki? If so what is mass rate of flow? is that the same as dv/dt?