Question

A small steam whistle (perfectly insulated and doing no shaft work) causes a drop of 0.8 kJ/kg the kinetic energy of the steam at entry is negligible, the velocity of the steam at exit is                                                 

      (a) 4 m/s                                                             (b) 40 m/s

      (c) 80 m/s                                                           (d) 120 m/s