Nitrogen flows without gain or loss of heat through a horizontal duct (cross-section is 1-ft by 2-ft throughout) at section 1 the pressure is 165 psia and the velocity is 65 ft/sec and the temperature is 55* F. at section 2 the pressure is 110 psia and the velocity is 107 ft/sec and the temperature is 35* F.
a) find the head loss in BTU/lb
b) the change in enthalpy between sections 1 and 2. (assume nitrogen is a perfect gas)