Monday, October 20, 2014

1–49

1–49 A vacuum gage connected to a tank reads 15 kPa at a
location where the barometric reading is 750 mm Hg. Determine the absolute pressure in the tank. Take rHg 13,590
kg/m
3
. Answer: 85.0 kPa
ANS
1-49The vacuumpressure reading of a tank isgiven. The absolutepressure inthe tank istobe determined. Properties The densityof mercuryisgiven tobe ρ= 13,590 kg/m 3 . Analysis The atmospheric (or barometric) pressure can be expressed as 15kPa Pabs kPa 0 . 100 N/m 1000 kPa 1 m/s kg 1 N 1 m) )(0.750 m/s )(9.807 kg/m (13,590 2 2 2 3 atm =             ⋅ = = h g P ρ Patm=750 mmHg Thenthe absolute pressure inthe tankbecomes kPa 85.0 = − = − = 15 100.0 vac atm abs P P P

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