a pitot tube (fig. 14-48) is used to determine the airspeed of an airplane. it consists of an outer tube with a number of small holes b (four are shown) that allow air into the tube; that tube is connected to one arm of a u-tube. the other arm of the u-tube is connected to hole a at the front end of the device, which points in the direction the plane is headed. at a the air becomes stagnant so that va = 0, At B, however, the speed of the air presumably equals the airspeed B of the plane. Use Bernoulli's equation to derive a formula giving the air speed in terms of the difference h in the liquid levels in that tube, the density rho of the liquid in the U-tube, and the density of air Pair. Suppose that the tube contains alcohol and the level difference h is 34.0 cm. What is the plane's speed relative to the air? The density of the air is 1.14 kg/m3 and that of alcohol is 810 kg/m3. Air Hole A Liquid Number Units