A system performs 120J work with no heat supplied to it. Calculate the change in internal energy of the system.
To calculate the change in internal energy of a system, you need to consider the first law of thermodynamics, which states that the change in internal energy (ΔU) of a closed system is equal to the heat (Q) added to the system minus the work (W) done by the system:
ΔU = Q - W
In this case, the problem states that no heat was supplied to the system (Q = 0), and the work done by the system is 120J. Therefore, we can calculate the change in internal energy as follows:
ΔU = 0J - 120J
= -120J
The change in internal energy is -120J. The negative sign indicates a decrease in the internal energy of the system.