1. What is Internal Energy?

Definition: Internal energy (ΔU) is the total energy contained within a thermodynamic system, representing the sum of all microscopic forms of energy.

Purpose: This calculator determines the change in internal energy of a system based on heat added and work done.

2. How Does the Calculator Work?

The calculator uses the First Law of Thermodynamics:

Where:

• \( \Delta U \) — Change in internal energy (Joules)
• \( Q \) — Heat added to the system (Joules)
• \( W \) — Work done by the system (Joules)

Explanation: The change in internal energy equals the heat added to the system minus the work done by the system.

3. Importance of Internal Energy Calculation

Details: Understanding internal energy changes is crucial for analyzing thermodynamic processes in engines, refrigerators, and chemical reactions.

4. Using the Calculator

Tips: Enter the heat added to the system (Q) and work done by the system (W) in Joules. Positive values indicate heat added/work done by system.

5. Frequently Asked Questions (FAQ)

Q1: What if work is done on the system?
A: Use a negative value for W when work is done on the system (compression).

Q2: What if heat leaves the system?
A: Use a negative value for Q when heat is removed from the system.

Q3: What are typical units for internal energy?
A: Joules (J) in SI units, but calories or BTUs may also be used with appropriate conversions.

Q4: Does this apply to ideal gases?
A: Yes, for ideal gases ΔU depends only on temperature change (ΔU = nCvΔT).

Q5: What about constant volume processes?
A: At constant volume (W=0), ΔU equals Q (heat added at constant volume).