Air flows through a constant cross-sectional area pipe with a pressure of 6 mpa, an enthalpy of 400.98 kj/kg, and a velocity of 1 m/s, it passes through a partially closed valve which reduces the pressure to 2 mpa. define a control volume and label the states. assuming air is an ideal gas determine the downstream a)-temperature , b)-specific volume , c)-velocity , and d)-the change in specific kinetic energy (in kj/kg).