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50 CHAPTER 4 The Integral Forms of the Fundamental Laws 4.1 a) No net force may act on the system: ΣvF=0. b) The energy transferred to or from the system must be zero: Q - W =0. c) If 332ˆˆˆ10()0nVVnij=⋅=⋅ -=vis the same for all volume elements then ΣvvFDDtVdm=∫,or ΣvvFDDtmV=().Since mass is constant for a system ΣvvFmDVDt=.Since DVDtaFmavvvv==,.Σ4.2 Extensive properties: Mass, m; Momentum, mVv;kinetic energy, 12mV2;potential energy, mgh; enthalpy, H. Associated intensive properties (divide by the mass): unity, 1; velocity, vV;V2/2; gh; H/m = h(specific enthalpy). Intensive properties: Temperature,T; time, t; pressure, p; density, r; viscosity, m. 4.3 (B) 4.4 System ()tV=1c.v.( )tV=1System ()ttV+ ∆=1V+2c.v.()ttV+ ∆=14.5 System ()tV=1V+2c.v.( )tV=1V+2System ()ttV+ ∆=2V+3c.v.()ttV+ ∆=1V+212123pump
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