Show that the cylinder contains $1.4 \times 10^{23}$ gas molecules.
Use kinetic theory to explain why, when the piston is moved so that the gas expands, the temperature of the gas falls.
The gas expands until its volume is $2.4 \times 10^{-3}\,\text{m}^3$ while the pressure is $2.3 \times 10^{5}\,\text{Pa}$ and the temperature is $288\,\text{K}$, as shown in Fig. 2.2. The average translational kinetic energy $E_K$ of one molecule of an ideal gas is given by $E_K = \frac{3}{2}kT$, where $k$ is the Boltzmann constant and $T$ is the thermodynamic temperature. Calculate the increase in internal energy $\Delta U$ of the gas during the expansion.
The work done by the gas during the expansion is $76\,\text{J}$. Use your answer in (i) to explain whether thermal energy is transferred to or from the gas as the expansion takes place.