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Unformatted text preview: Solution to the problems in recitation 4 Problem 1 Known: Gas in ideal piston-cylinder assembly undergoes a quasistatic/quasiequilibrium process. Find: Absolute pressure in and out the assembly; absolute pressure Absolute pressure after gas expands Force exerted by diver at the final volume Work done by gas, and by diver Schematic and Given Data: ρ = 1100 kg/m 3 , g = 9.81 m/s 2 , p atm = 1 bar = 100 kPa, h = 100m, A = 0.02 m 2 Assumptions: 1. gas is a closed system 2. quasiequilibrium process 3. No change in KE and PE 4. Dimension of the assembly is small compared to the depth. Analysis: a) From hydrostatic, p abs,out = p atm + ρ gh, where h is the depth and ρ is the water density. p abs,out = 100 kPa + (1100 kg/m 3 )(9.81 m/s 2 )(100m) = 100 kPa + 1079 kPa = 1179 kPa b) For ideal piston/cylinder assembly, initially the pressures inside and outside are balanced. p abs,in = p abs,out = 1179 kPa c) p 1 = 1179 kPa, V 1 = 0.01m 3 ; V 2 = 0.011 m 3 , p 2 = ?...
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- Fall '08
- Thermodynamics, kPa, Qcv