The change in internal energy (ΔU) of a system can be calculated using the first law of thermodynamics:
ΔU = Q - W
Where: ΔU is the change in internal energy Q is the heat transferred to the system W is the work done by the system
In this case, the heat transferred to the system (Q) is 645 J, and the work done by the system (W) is 450 J. Substituting these values into the equation, we get:
ΔU = 645 J - 450 J ΔU = 195 J
Therefore, the change in internal energy (ΔU) is 195 J.