"Change in internal energy" refers to the difference between the initial and final internal energy of a system. It is a measure of the energy transferred to or from a system through heating, work, or other processes.
The change in internal energy can be calculated using the equation ΔU = Q - W, where ΔU is the change in internal energy, Q is the heat added to the system, and W is the work done by the system.
A change in internal energy can be caused by heat transfer, work, chemical reactions, changes in temperature, and changes in volume or pressure of the system.
The change in internal energy is an important concept in thermodynamics as it helps us understand the energy flow in a system and how it is affected by different processes. It is also used to determine the efficiency of a system and predict its behavior under different conditions.
The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or converted. The change in internal energy is a direct result of this law as it accounts for the energy transferred to or from a system through various processes.