Air flows down a 20 mm diameter pipe which has a length of 0.8 m. if the velocity at the inlet to the pipe is 200 m/s and its temperature is 30°c, find the average friction factor if the flow is choked at the exit to the pipe. assume the flow to be adiabatic.

Abarometer contains mercury with a density of 13600 kg/m3. atmospheric conditions are 95.8 kpa and 20 °c at 20 °c, the vapor pressure of the mercury is 0.000173 kpa. the column of mercury will rise to a height of most nearly. select one: a)- 0.38 m b)- 0.82 m c)- 0.48 m d)- 0.72 m