Concept explainers
A Pitot tube is a device used to measure the velocity of a fluid, typically, the airspeed of an aircraft. The failure of a pitot tube is credited as the cause of Austral Lines Aéreas flight 2553 crash in October 1997. The pitot tube had frozen, causing the instrument to give a false reading of slowing speed. As a result, the pilots thought the plane was slowing down, so they increased the speed and tried to maintain their attitude by lowering the wing slats. Actually, they were flying at such a high speed that one of the slats ripped off, causing the plane to nosedive, the plane crashed at a speed 745 miles per hour.
In the pitot tube, as the fluid moves, the velocity creates a pressure difference between the ends of a small tube. The tubes are calibrated to relate the pressure measured to a specific velocity. This velocity is a function of the pressure difference (P, in units of pascals) and the density of the fluid (ρ in units of kilograms per cubic meter)
Fluid | Specific Gravity |
Acetone | 0.79 |
Citric acid | 1.67 |
Glycerin | 1.26 |
Mineral Oil | 0.90 |
- a. Show the resulting data trendline, with equation and R2 value, on the appropriate graph type (xy scatter, semilog, or log–log) to make the data appear linear.
- b. Determine the value and units of the density for each data set using the trendline equation.
- c. From the chart at left, match each data set (A, B) with the correct fluid name according to the results of the density determined from the trendlines.
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