4.18 WP Air enters a

horizontal, constant-diameter

heating duct operating at steady

state at 290 K, 1 bar, with a

volumetric flow rate of 0.25

m³/s, and exits at 325 K, 0.95

bar. The flow area is 0.04 m².

Assuming the ideal gas model

with k = 1.4 for the air,

determine (a) the mass flow

rate, in kg/s, (b) the velocity at

the inlet and exit, each in m/s,

and (c) the rate of heat transfer,

in kW.