Given:
The thermal energy added to the system is Q = 90 J
The work done by the system on the surroundings is W = 30 J
To find the change in internal energy.
Explanation:
According to the first law of thermodynamics, the change in internal energy can be calculated by the formula
[tex]\Delta U=\text{ Q-W}[/tex]On substituting the values, the change in internal energy will be
[tex]\begin{gathered} \Delta U\text{ =90-30} \\ =60\text{ J} \end{gathered}[/tex]Final Answer: The chage in internal energy is 60 J (option D)
