When air of the atmosphere rises up,it cools. Why?
(N/A) As air rises,the atmospheric pressure decreases. Due to this decrease in pressure,the air parcel expands. Since the expansion occurs rapidly,it can be considered an adiabatic process where the air does work on the surroundings at the expense of its internal energy. According to the first law of thermodynamics,$dQ = dU + dW$. For an adiabatic process,$dQ = 0$,so $dU = -dW$. Since the air does positive work $(dW > 0)$,its internal energy decreases $(dU < 0)$,which leads to a decrease in temperature.
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View SolutionDuring an adiabatic process,the pressure of a gas is found to be proportional to the cube of its temperature. The ratio of $\frac{C_P}{C_V}$ for the gas is
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Statement-$II$: In the above case,when work is done on the gas,the temperature of the gas would rise.
Choose the correct answer from the options given below:
Statement-$I$: When $\mu$ amount of an ideal gas undergoes adiabatic change from state $(P_1, V_1, T_1)$ to state $(P_2, V_2, T_2)$,the work done is $W = \frac{\mu R(T_2 - T_1)}{1 - \gamma}$,where $\gamma = \frac{C_P}{C_V}$ and $R$ is the universal gas constant.
Statement-$II$: In the above case,when work is done on the gas,the temperature of the gas would rise.
Choose the correct answer from the options given below:
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