1. The problem statement, all variables and given/known data A boat with mass M is at rest. Balls are thrown at the back of the boat, where each ball has mass of m, and the balls are being thrown with the mass rate of σ kg/s (the rate is continuous). The balls are being collected inside the boat (inelastic collision). Find velocity and position of the boat as a function of time. 2. Relevant equations Δmu + MV = (Δm + M)(V + ΔV) 3. The attempt at a solution I thought I could use the rocket equation for this, but I had trouble figuring it out because I wasn't sure if I can assume ƩF = 0.