# MECH 230 Study Guide - Quiz Guide: Mass Flux, Polytropic Process, Ideal Gas

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22 Nov 2012

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Pgauge=Pabs-Patm

P1 = P2 + ρgL

W=V1V2PdV

Polytropic Process:

n≠1: W=P2V2-P1V11-n

n=1: W=P2V2lnV2V1

W=P1V1lnV2V1

n=0: const. P: W=PV2-V1

const. V: W = 0

Work by or Heat to the system is positive

Work on or Heat from the system is negative

Adiabatic: Q = 0

∆E=-W

Isothermal: T = const;

U = 0, unless state is changingΔ

E2 – E1 = Q – W

∆E=∆KE+∆PE+∆U=Q-W

12mv22-v12+mgh2-h1+12kx22-x12+mT1T2cvdT=Q-W

∆U=U2-U1=Q-W

Wcycle=Qcycle

Power Cycle Wcycle>0 Qin>Qout

Refrigeration Cycle Wcycle<0 Qin<Qout

Liquid – Vapour

(UNDER DOME)

x=mgmg-mf

v=vf+xvg-vf

u=uf+xug-uf

h=hf+xhg-hf

Compressed liquids: If P is small,

u(P,T) ~ uf(T)

v(P,T) ~ vf(T)

h(P,T) = hf(T) + vf(P-Psat(T*))

IDEAL GASES

z=PvRT; z=1 for ideal gas

PV=MRT

PV=nRT

Pv=RT

T2T1=P2P1n-1n=v1v2n-1

W=MR(T2-T1)1-n

cpT=cvT+R

cpT=cvT+R

kT=cpcv

cvT=RkT-1

cp(T)=kTRkT-1

Other

h=u+Pv

incompressible substances

Cp=Cv=C

CONTROL VOLUME ANALYSIS

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