1. The problem statement, all variables and given/known data Here http://imgur.com/a/4LRM6 2. Relevant equations The equation is given int he question 3. The attempt at a solution gas will stop flowing when the pressure inside the gas is equal to that of the surroundings. I calculated the final mass of gas inside the cube. Then i calculated the change in mass of the gas and i got that to be c^2*L^3/3*(1/p-1/Po) then i divided by t and converted L/t=c. However i don't think this is correct as i don't see why the rate of flow of gas should be constant and also my answer seems to be independant of a which seems counter intuitive.