Answer to Question #200656 in Mechanics | Relativity for Master j

Question

i. Distinguish between gauge pressure and absolute pressure.

ii A U-tube mercury manometer is used to measure the pressure of a gas in a metal container. If the gauge pressure of the gas is 13 kPa what will be the difference mercury levels in the two arms of the U-tube.

Density of mercury = 13600 kg/m3

Atmospheric pressure = 101 kPa

Answer 1

Gauge pressure is measured with reference to atmospheric pressure. Therefore, fluctuations in atmospheric pressure due to change in altitude or weather conditions directly influence the gauge pressure readings. On the other hand, absolute pressure uses a perfect vacuum as its datum point.$Pgas= Patm +hpg$

13 Kpa = 101 Kpa + (13600 kg/m3 × 9.81× h)/1000

h= 65cm