Question

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Jos este delta u123

Answer 1

Răspuns:

a)Q123= Q12+Q23

Q12=νCvΔT12=3/2νR(T2-T1)= 3/2(νRT2-νrT1)=3/2(p2V2-p1V1)

din grafic p2=4p1, V2=V1

=>Q12=1,5(4p1V1-p1V1)=1,5* 3p1V1= 4,5 p1V1

Q23=νCpΔT23

Cp=Cv+R=5R/2

Q23=5/2νR(T3-T2)=5/2(p3V3-p2V2)

p3=p2=4p1

V3=8V1

=> Q23=2,5(4 p1 8 V1- 4p1V1)= 70p1v1

=>Q123=4,5 p1V1+70 p1V1=74,5p1V1= 74,5 *10^5 *2=14,9 Mj

b)L123=L12+L23

L12- lucrul mecanic intr-o izocora

=> L12=0

=>L123=L23

L23=νRΔT23=νR(T3-T2)=νRT3-νRT2

= p3V3-p2v2= 4p1 8V1- 4p1V1=32p1V1-4 p1V1=28p1V1=28*2*10^5=5,6 Mj

c)ΔU123=ΔU13(energia interna nu depinde de starile intermediare)

ΔU13=νCvΔT13=3/2νR(T3-T1)=1,5(p3V3-p1v1)=31p1V1= 31*2*10^5= 6,2 Mj

Explicație:

Q12- caldura izocora

Q23- caldura izobara