`DeltaU=q+w`, is mathematical expression for

Options

A. first law of thermodynamics
B. second law of thermodynamics
C. third law of thermodynamics
D. zeroth law of thermodynamics

Answer

To solve the question regarding the expression \( \Delta U = q + w \), we can break it down step by step:

### Step-by-Step Solution:

1. **Understanding the Symbols**:
- \( \Delta U \): This represents the change in internal energy of a system.
- \( q \): This denotes the heat exchanged by the system. It can be positive (heat absorbed) or negative (heat released).
- \( w \): This represents the work done on or by the system. Similar to heat, it can also be positive (work done on the system) or negative (work done by the system).

2. **Identifying the Law**:
- The equation \( \Delta U = q + w \) is a fundamental equation in thermodynamics. It relates the internal energy change of a system to the heat added to the system and the work done on or by the system.

3. **Connecting to Thermodynamics**:
- This equation is derived from the First Law of Thermodynamics, which states that energy cannot be created or destroyed, only transformed from one form to another. In essence, the internal energy of a system changes due to heat transfer and work done.

4. **Conclusion**:
- Therefore, the expression \( \Delta U = q + w \) is a mathematical representation of the First Law of Thermodynamics.

### Final Answer:
The expression \( \Delta U = q + w \) is a mathematical expression for the **First Law of Thermodynamics**.

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