What is the change in internal energy of a system that releases 1275 J of heat to the surroundings and is compressed so that 235 J of work are done on the system?
To calculate the change in internal energy of a system, you can use the First Law of Thermodynamics, which states that the change in internal energy (ΔU) of a system is equal to the heat (Q) added to or removed from the system minus the work (W) done by or on the system. Mathematically, it is expressed as:
ΔU = Q - W
In this case, the system releases 1275 J of heat to the surroundings (Q = -1275 J) and is compressed so that 235 J of work is done on the system (W = -235 J). Note that the negative sign indicates that heat is released or work is done on the system.
Substituting these values into the equation, we have:
ΔU = -1275 J - (-235 J)
Simplifying this expression:
ΔU = -1275 J + 235 J
ΔU = -1040 J
Therefore, the change in internal energy of the system is -1040 J.