In thermodynamics, if the heat added to a system equals the work done by the system, the change in internal energy is

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In thermodynamics, if the heat added to a system equals the work done by the system, the change in internal energy is

The change in internal energy is determined by the balance between heat added and work done: ΔU = q − w. When the heat entering the system equals the work the system does (q = w), the internal energy change is zero. In other words, energy flows in as heat and flows out as work, leaving the microscopic energy content unchanged. For example, supplying 100 J of heat while the system does 100 J of work results in no net change in internal energy. If heat exceeded work, ΔU would be positive; if work exceeded heat, ΔU would be negative. This outcome holds regardless of the type of gas.

The change in internal energy is determined by the balance between heat added and work done: ΔU = q − w. When the heat entering the system equals the work the system does (q = w), the internal energy change is zero. In other words, energy flows in as heat and flows out as work, leaving the microscopic energy content unchanged. For example, supplying 100 J of heat while the system does 100 J of work results in no net change in internal energy. If heat exceeded work, ΔU would be positive; if work exceeded heat, ΔU would be negative. This outcome holds regardless of the type of gas.

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