1. The problem statement, all variables and given/known data A rocket ascends from rest in Earth's gravitational field, by ejecting exhaust with constant speed u. Assume that the rate at which mass is expelled is given by dm/dt = −γm where m is the instantaneous mass of the rocket and γ is a constant; and that the rocket is retarded by air resistance with a force mbv where b is a constant. Determine the velocity of the rocket as a function of time. Here is a hint: The terminal velocity is ( γu−g )/b. Calculate the time when the velocity is one-half of the terminal velocity. Data: u = 31.9 m/s; b = 1.2 s−1. 2. Relevant equations dp/dt=F=m(dv/dt) 3. The attempt at a solution I get dv=-udm-(g+bv)dt; dm=-γm so dv=uγ-(g+bv)dt solving for v: v(t)=(1/b)e^((-uγ/b)t)-(g/b) the problem I am running into is what is gamma, because I have no inital condition to apply, and I'm fairly sure the solution to the diff eq is correct.