Question 797: Thermodynamics & KTG

Question

There are two samples A and B of a certain gas, which are initially at the same temperature and pressure. Both are compressed from volume v to $\frac{\mathrm{v}}{2}$. Sample A is compressed isothermally while sample B is compressed adiabatically. The final pressure of $A$ is

Accepted Answer

For an isothermal process.
$$P_1 V_1=P_2 V_2$$
Given that $\mathrm{V}_2=\frac{\mathrm{V}_1}{2}$. It can be clearly understood that for $\mathrm{P}_2 \mathrm{~V}_2$ to remain constant,
$\mathrm{P}_2=2 \mathrm{P}_1\quad	ext{.... (i)}$.
For an adiabatic process, $\mathrm{PV}^\gamma=$ constant.
$$\begin{aligned}
& \mathrm{P}_1 \mathrm{~V}_1^\gamma=\mathrm{P}_2 \mathrm{~V}_2^\gamma \
& \mathrm{P}_2=\mathrm{P}_1\left(\frac{\mathrm{~V}_1}{\mathrm{~V}_2}ight)^\gamma=2 \mathrm{P}_1^\gamma\quad	ext{.... (ii)}
\end{aligned}$$
$\gamma$ is always greater than 1. From equations (i) and (ii), it can be seen that the pressure change in an adiabatic process would be greater than that in an isothermal process for the same change in volume.

Answer

twice that of $B$.

Answer

equal to that of $B$.

Answer

more than that of B.

Answer

less than that of B .

Thermodynamics & KTG

There are two samples A and B of a certain gas, which are initially at the same temperature and pressure. Both are compressed from volume v to \frac{\mathrm{v}}{2}. Sample A is compressed isothermally while sample B is compressed adiabatically. The final pressure of A is

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