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11.Thermodynamics
hard
A sample of an ideal gas is taken through a cycle a shown in figure. It absorbs $50J$ of energy during the process $AB$, no heat during $BC$, rejects $70J$ during $CA.$ $40J$ of work is done on the gas during $BC$. Internal energy of gas at $A$ is $1500J$, the internal energy at $C$ would be ........ $J$
A
$1590 $
B
$1620 $
C
$1540 $
D
$1570 $
Solution
(a) $\Delta {W_{AB}} = 0$ as $ V =$ constant
$\therefore$ $\Delta {Q_{AB}} = \Delta {U_{AB}} = 50J$ (Given)
${U_A} = 1500J$ $\therefore$ ${U_B} = (1500 + 50)J = 1550J$
$\Delta {W_{BC}} = – \Delta {U_{BC}} = – 40J$(Given)
$\therefore$ $\Delta {U_{BC}} = 40J$ $\therefore$ ${U_C} = (1550 + 40)J = 1590J$
Standard 11
Physics
