1. The problem statement, all variables and given/known data Tank (mass M) contains water (mass m). L is distance from centre of mass of container to pipe.(x) is noted as the direction to the right. Pipe is small compared to tank. Tank is sitting on a frictionless surface Open the tap, water flows out. After, where is the tank and which way is it moving? Explain your answer in terms of forces on the tank. see link two posts down for picture... I need to find expression for the distance travelled - expression for the final velocity 2. Relevant equations 3. The attempt at a solution I assume as the water flows out, the tank would move to the left as the water is flowing out of the tank to the right so there would be an equal but opposite in direction force acting on the tank. Hence the tank moves to the left. But I dont know how to work out where the tank is, given There is no variables to work with. Please correct anything that is wrong with my logic above?