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Internal energy is a fundamental concept in thermodynamics that represents the total energy contained within a thermodynamic system. It includes both the kinetic energy of molecules and the potential energy from molecular interactions.
The calculator uses the thermodynamic relation:
Where:
Explanation: This formula relates the internal energy of a system to its Helmholtz free energy, temperature, and entropy, providing a fundamental thermodynamic relationship.
Details: Calculating internal energy is crucial for understanding energy transformations in thermodynamic systems, analyzing heat transfer processes, and studying the behavior of materials under different temperature conditions.
Tips: Enter Helmholtz free energy in joules, temperature in kelvin, and entropy in joules per kelvin. Temperature must be non-negative (≥0 K).
Q1: What is the physical significance of internal energy?
A: Internal energy represents the total microscopic energy of a system, including molecular kinetic energy and intermolecular potential energy.
Q2: How does internal energy differ from enthalpy?
A: Internal energy (U) is the total energy contained within a system, while enthalpy (H) includes both internal energy and the product of pressure and volume (H = U + PV).
Q3: Can internal energy be measured directly?
A: No, internal energy cannot be measured directly. It is typically calculated from other measurable thermodynamic properties using appropriate equations.
Q4: What are typical units for internal energy?
A: Internal energy is measured in joules (J) in the SI system, though other energy units like calories or electronvolts may be used in specific contexts.
Q5: How does temperature affect internal energy?
A: For most substances, internal energy increases with temperature as molecular motion becomes more vigorous, though the relationship depends on the specific heat capacity of the material.