1. The problem statement, all variables and given/known data Here is the data I have been given; mass = 3.4*10^6 kg (at lift off) mass of first stage propellants = 2.0*10^6 propellant consumption rate = 1.4*10^4 kg/s g = 9.8 m/s/s Find the thrust of the engines at lift-off. 2. Relevant equations a = T-mg/m 3. The attempt at a solution So mg = (3.4*10^6)*9.8 = 3.332*10^7 m = 3.4*10^6 ∴a = T-3.332*10^7/3.4*10^6 I have two unknowns here, I thought there might be a way of finding either acceleration or thrust using mass, propellant mass and propellant consumption? I have searched through my HSC texts and haven't been able to find an equation where I can find 'a' or 'T' without needing one to find the other.