First Law of Thermodynamics: Energy Conservation The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed or t...
The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed or transferred. This means that the total amount of energy in an isolated system remains constant, regardless of the changes occurring within the system.
Internal Energy:
Internal energy refers to the total energy of all the particles within a system, including kinetic and potential energy. It depends on factors like temperature, pressure, and the system's arrangement.
Work Done:
Work done by a system represents the amount of energy transferred to or by the system during a thermodynamic process. It is an extensive property that depends on the changes in the system's energy and configuration.
Examples:
Increasing temperature: When you heat a pot of water, the internal energy of the water increases, causing its temperature to rise. This is because energy is transferred to the water molecules, increasing their kinetic and potential energy.
Adding pressure to a gas: When you inflate a balloon, the internal energy of the gas increases due to the increase in potential energy of the gas molecules.
Work done during a cycle: When a heat engine runs, the internal energy of the working fluid decreases as it does work on the surroundings. This is why a cycle has a net work output.
Key Differences:
The first law applies to isolated systems, meaning it cannot be applied to a system that exchanges energy with the outside environment.
Internal energy is a state property, meaning its value depends only on the current state of the system, not on its past history.
Work done is an extensive property, meaning its value depends on the entire path of a thermodynamic process, even if the final state is the same as the initial state