Question $3(10$ points$)$

As shown in the figure, we heated the helium inside the balloon, raising the temperature to $60C$

and increasing the pressure from $1$ bar to $3$ bar. Consequently, the volume expanded to $V_2.$

Afterward, we allowed the balloon to cool back down to its initial temperature $($ambient

temperature$),$ during which the volume decreased to $\frac{2}{3}{V}_2.$ What is the change in the internal

energy of the helium during this process, from the initial state $($state $1)$ to the final state $($state $3)?$

$(10$ marks$)$