Isothermal process on p-V, T-V, and p-T diagrams
Isothermal process on p-V, T-V, and p-T diagrams
Isothermal process on p-V, T-V, and p-T diagrams
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Clicker questi<strong>on</strong> 9<br />
C<strong>on</strong>sider the p-V diagram below in which the system evolves reversibly<br />
al<strong>on</strong>g the adiabat from state a to state b. How much work, W, does the<br />
system do <strong>on</strong> its envir<strong>on</strong>ment?<br />
a) 20 kJ b) –20 kJ<br />
p (kNm –2 )<br />
16<br />
1<br />
b<br />
W<br />
adiabat<br />
1 8<br />
a<br />
V (m 3 )<br />
c) 24 kJ d) –24 kJ<br />
e) 32 kJ f) –32 kJ<br />
g) not enough informati<strong>on</strong> to tell<br />
ΔE int = 0 – W = 3Δ(nRT) = 3Δ(pV)<br />
= 3(16 – 8) = 24 ⇒ W = –24 kJ<br />
E int = nC V T = n3RT (for a polyatomic gas)<br />
first law: ΔE int = Q – W ideal gas law: pV = nRT<br />
PHYS 1101, Winter 2009, Prof. Clarke 23
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