JEE MainPhysicstoughThermodynamics

Figure shows the variation of internal energy "U" with the
density " $\rho$ " of one mole of ideal diatomic gas. Process BA is a
part of rectangular hyperbola. If the work done by gas in the process BA
is 7n joules. Find n ?

Show answer and solution

For rectangular hyperbola
XY = constant

U\rho =

constant

nC_{V}T\rho =

constant

n\frac{5}{2}RT\frac{M}{V} =

constant

\frac{5}{2}P\frac{VM}{V} =

constant

\Rightarrow

P = constant
(isobaric process)

\Delta U_{B \rightarrow A} = 37 - 2 = 35J = \frac{5}{2}nR\Delta T

14J = nR\Delta T

\therefore

W = 14J

Source: Grass-G / P-22 Physcis Paper 19 Dec Eng..docx

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