2) an ideal gas flows through a horizontal tube at steady state. no heat is added and no shaft work is done. the cross- sectional area of the tube changes with length and this causes the velocity to change. derive an equation relating the temperature to the velocity of the gas. if nitrogen at 150 °c flows past one section of the tube at a velocity of 2.5 m/s, what its temperature at another section where its velocity is 50 m/s? cp = 7/2 r.