Mercury is often used in barometers as depicted in Figure. This is because the vapor pres...

Mercury is often used in barometers as depicted in Figure. This is because the vapor pres sure of mercury is low enough to be ignored, and because it is so dense (sp. gr. = 13.6) the tube can be shortened considerably. With the atmospheric pressure found in Problem (99.9 kN/m2 at 30°C), determine the column height in meters (and feet) if mercury is used.

Figure

Problem

The simple barometer in Figure uses water at 30°C as the liquid indicator. The liquid col umn rises to a height of 9.8 m from an original height of 8.7 m in the vertical tube. Compute the new atmospheric pressure, neglecting surface tension effects. What is the percentage error if the direct reading is used and vapor pressure is ignored?