A small steam whistle (perfectly insulated and doing no shaft work) causes a drop of 0.8 kJ/kg in the enthalpy of steam from entry to exit. If the kinetic energy of the steam at entry is negligible, the velocity of the steam at exit is
4 m/s
40 m/s
80 m/s
120 m/s
change in enthalpy is converted to kinetic energy of the fluid (neglecting shaft work, heat , potential energy )
H= V2 / 2g which gives V= 120 m/s