Thermodynamics and Thermochemistry - Result Question 79
####4. During compression of a spring the work done is $10 kJ$ and 2 $kJ$ escaped to the surroundings as heat. The change in internal energy, $\Delta U$ (in $kJ$ ) is
(2019 Main, 9 April II)
(a) 8
(b) -12
(c) 12
(d) -8
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Solution:
- In the given system, during the compression of a spring the workdone is $10 kJ$ and $2 kJ$ of heat is escaped to the surroundings. So, $q=-2 kJ$ and $W=10 kJ$
According to the first law of thermodynamics,
$$ \begin{aligned} & \Delta U=q+W=-2 kJ+10 kJ \ & \Delta U=8 kJ \end{aligned} $$
The change in internal energy, $\Delta U$ (in $kJ$ ) is $8 kJ$.
