1. What is the Internal Energy Equation?

The internal energy equation (ΔU = q + w) represents the first law of thermodynamics, stating that the change in internal energy of a system equals the heat added to the system plus the work done on the system.

2. How Does the Calculator Work?

The calculator uses the internal energy equation:

Where:

• \( \Delta U \) — Change in internal energy (J)
• \( q \) — Heat transferred to the system (J)
• \( w \) — Work done on the system (J)

Explanation: This fundamental equation of thermodynamics shows that the internal energy of a system changes through heat transfer and work interactions with its surroundings.

3. Importance of Internal Energy Calculation

Details: Calculating internal energy changes is essential for understanding thermodynamic processes, analyzing energy conservation in closed systems, and predicting system behavior in various engineering and scientific applications.

4. Using the Calculator

Tips: Enter heat (q) and work (w) values in joules. Positive values indicate energy added to the system, while negative values indicate energy removed from the system.

5. Frequently Asked Questions (FAQ)

Q1: What is the sign convention for q and w?
A: Positive q indicates heat added to the system; positive w indicates work done on the system. Negative values indicate the opposite.

Q2: How does this relate to the first law of thermodynamics?
A: This equation is the mathematical statement of the first law of thermodynamics for closed systems.

Q3: What are typical units for internal energy?
A: The SI unit is joules (J), though calories or other energy units may be used with appropriate conversion factors.

Q4: Does this equation apply to all systems?
A: This form applies specifically to closed systems where only heat and work can cross the system boundary.

Q5: How is internal energy different from enthalpy?
A: Enthalpy (H) includes both internal energy and the product of pressure and volume (H = U + PV), making it more useful for constant-pressure processes.