1. The problem statement, all variables and given/known data An incompressible heated gas of constant temperature and pressure flows along an infinitely long tube at an unspecified velocity v1; a pressure of P1; and a density of p1 into an unheated open area of infinite volume containing the same gas at a lower pressure of P2; a density of p2,; and an effective velocity v2 of 0 m/s. The pipe is horizontal. Find the velocity of the gas inside the tube, ignoring friction and head losses. 2. Relevant equations Bernoulli's equation, maybe 3. The attempt at a solution Since the pipe is horizontal, h1 and h2 are treated as 0, cancelling out the pgh terms on each side of the equation. Since v2 is also 0, the .5p2v22 is eliminated. That leaves us with: P1 + .5p1v12 = P2 Since P1 > P2 in this situation, the answer is always going to be the square root of a negative number. Common sense tells me that the gas will flow from a region of high pressure to a region of low pressure, so it should flow out of the tube; sadly, it seems that I am applying Bernoulli's equation incorrectly in attempting to form a basic model of that effect. That, or something else is terribly wrong with the way the scenario is laid out (this is my own thought experiment; it is not homework, and no teacher is to blame for this problem). Just looking at the reduced equation, it's all wrong. There's no way the high pressure value plus PLUS the squared velocity is going to equal the low pressure value. But the flow velocity in the tube is going to be non-zero since gas will be constantly leaving the tube ad infinitum, while the velocity outside of the tube is going to be zero since it is effectively a section of tube with a cross-sectional area approaching infinity.