Thermodynamics

Chapter 1 | 491–112E Consider a U-tube whose arms are open to theatmosphere. Now equal volumes of water and light oil (r 49.3 lbm/ft 3 ) are poured from different arms. A person blowsfrom the oil side of the U-tube until the contact surface of thetwo fluids moves to the bottom of the U-tube, and thus theliquid levels in the two arms are the same. If the fluid heightin each arm is 30 in, determine the gage pressure the personexerts on the oil by blowing.P gage = 370 kPaAir45 cm50 cmOil SG = 0.79Gasoline SG = 0.7022 cmPipe10 cmWaterMercurySG = 13.6AirFIGURE P1–114OilWaterFIGURE P1–112E30 in1–115 Repeat Prob. 1–114 for a pressure gage reading of180 kPa.1–116E A water pipe is connected to a double-U manometeras shown in Fig. P1–116E at a location where the localatmospheric pressure is 14.2 psia. Determine the absolutepressure at the center of the pipe.1–113 Intravenous infusions are usually driven by gravityby hanging the fluid bottle at sufficient height to counteractthe blood pressure in the vein and to force the fluid into thebody. The higher the bottle is raised, the higher the flow rateof the fluid will be. (a) If it is observed that the fluid and theblood pressures balance each other when the bottle is 1.2 mabove the arm level, determine the gage pressure of theblood. (b) If the gage pressure of the fluid at the arm levelneeds to be 20 kPa for sufficient flow rate, determine howhigh the bottle must be placed. Take the density of the fluidto be 1020 kg/m 3 .35 inWaterpipeOil SG = 0.8060 inOil SG = 0.8040 in15 inMercurySG = 13.61.2 mFIGURE P1–113P atmIV bottle1–114 A gasoline line is connected to a pressure gagethrough a double-U manometer, as shown in Fig. P1–114. Ifthe reading of the pressure gage is 370 kPa, determine thegage pressure of the gasoline line.FIGURE P1–116E1–117 It is well-known that the temperature of the atmospherevaries with altitude. In the troposphere, which extendsto an altitude of 11 km, for example, the variation of temperaturecan be approximated by T T 0 bz, where T 0 is thetemperature at sea level, which can be taken to be 288.15 K,and b 0.0065 K/m. The gravitational acceleration alsochanges with altitude as g(z) g 0 /(1 z/6,370,320) 2 whereg 0 9.807 m/s 2 and z is the elevation from sea level in m.Obtain a relation for the variation of pressure in the troposphere(a) by ignoring and (b) by considering the variation ofg with altitude.1–118 The variation of pressure with density in a thick gaslayer is given by P Cr n , where C and n are constants.Noting that the pressure change across a differential fluidlayer of thickness dz in the vertical z-direction is given asdP rg dz, obtain a relation for pressure as a function of