A thin tube of uniform cross section is sealed at both ends. It lies horizontally, the middle 5cm containing mercury and the parts on its two sides containing air at the same pressure p. when the tube is held at and angle of `60_(@)` with the vertical, the length of the air column above and belw the mercury pellet are 46cm and 44.5cm respectively. Calculate the ressure - in centimeters of mercury, The timperature of the system is kept at `30_(@)C`.