When a slender body held transversely is tested in a wind tunnel it is found that the decrease in velocity in the wake is approximately linear. It decreases from the undis- turbed velocity u, at double the solid width to 0.2U, at the axis, the pressure in the wake being constant throughout and the same as that in the undisturbed stream. If such a body of 1.5m width moves, under dynamically similar conditions, through still air at 150 m s', calculate the drag on the solid per unit length and the drag coefficient. The air is at 5 C and a pressure of 510 mm of mercury. Take the density of mercury as 13.6 10 kg m-3 and the gas constant for air as R=287 Jkg K-.