Factors that Increase Internal Energy

Oct 13, 2025 by wbrum.org 100 views

Introduction

In thermodynamics, the internal energy of a system is a fundamental concept that plays a crucial role in understanding various physical processes. It is defined as the total energy of a system, including both kinetic energy and potential energy of its particles. In this article, we will explore the factors that increase the internal energy of a system, and discuss the correct answer among the given options.

What is Internal Energy?

Internal energy is a measure of the total energy of a system, including both kinetic energy and potential energy of its particles. It is a state function, meaning that its value depends only on the current state of the system, and not on the path by which the system reached that state. The internal energy of a system can be increased by various means, such as adding heat, doing work on the surroundings, or expanding the system against an external pressure.

Factors that Increase Internal Energy

Adding Heat to the System

When heat is added to a system, the energy of the particles in the system increases, resulting in an increase in the internal energy of the system. This is because the heat energy is transferred to the system, causing the particles to gain kinetic energy and move more rapidly. As a result, the internal energy of the system increases.

Doing Work on the Surroundings

When a system does work on the surroundings, the energy of the system decreases, resulting in a decrease in the internal energy of the system. This is because the work done by the system is transferred to the surroundings, causing the energy of the system to decrease. Therefore, doing work on the surroundings does not increase the internal energy of the system.

Adding Heat to the System and Having the System Do Work on the Surroundings

When heat is added to a system and the system does work on the surroundings, the energy of the particles in the system increases, resulting in an increase in the internal energy of the system. However, the work done by the system is transferred to the surroundings, causing the energy of the system to decrease. As a result, the net change in the internal energy of the system is the sum of the heat added and the work done by the system.

A Volume Decompression

When a system undergoes a volume decompression, the energy of the particles in the system increases, resulting in an increase in the internal energy of the system. This is because the system is expanding against an external pressure, causing the energy of the particles to increase.

Conclusion

In conclusion, the internal energy of a system is always increased by adding heat to the system and having the system do work on the surroundings. This is because the heat energy is transferred to the system, causing the particles to gain kinetic energy and move more rapidly, resulting in an increase in the internal energy of the system. Additionally, the work done by the system is transferred to the surroundings, causing the energy of the system to decrease, but the net change in the internal energy of the system is the sum of the heat added and the work done by the system.

Answer

The correct answer is B. Adding heat to the system and having the system do work on the surroundings.

Discussion

What are some other factors that can increase the internal energy of a system?
How does the internal energy of a system change when a system undergoes a phase transition?
Can you think of any real-world examples where the internal energy of a system is increased by adding heat and doing work on the surroundings?

References

Cengel, Y. A., & Boles, M. A. (2015). Thermodynamics: An Engineering Approach. McGraw-Hill Education.
Kittel, C., & Kroemer, H. (1980). Thermal Physics. W.H. Freeman and Company.
Halliday, D., Resnick, R., & Walker, J. (2013). Fundamentals of Physics. John Wiley & Sons.
The Internal Energy of a System: Q&A =====================================

Introduction

In our previous article, we discussed the factors that increase the internal energy of a system. In this article, we will answer some frequently asked questions related to the internal energy of a system.

Q&A

Q: What is the difference between internal energy and enthalpy?

A: Internal energy is the total energy of a system, including both kinetic energy and potential energy of its particles. Enthalpy, on the other hand, is a measure of the total energy of a system, including both internal energy and the energy associated with the pressure and volume of the system.

Q: Can you give an example of a system where the internal energy is increased by adding heat and doing work on the surroundings?

A: Yes, a good example is a steam engine. In a steam engine, heat is added to the system (the steam) and the system does work on the surroundings (by turning a turbine). As a result, the internal energy of the system increases.

Q: How does the internal energy of a system change when a system undergoes a phase transition?

A: When a system undergoes a phase transition, the internal energy of the system can change significantly. For example, when water freezes, the internal energy of the system decreases as the molecules slow down and come together to form a crystal lattice.

Q: Can you think of any real-world examples where the internal energy of a system is increased by adding heat and doing work on the surroundings?

A: Yes, a good example is a power plant. In a power plant, heat is added to the system (the steam) and the system does work on the surroundings (by turning a turbine) to generate electricity.

Q: What is the relationship between internal energy and temperature?

A: The internal energy of a system is directly proportional to the temperature of the system. As the temperature of a system increases, the internal energy of the system also increases.

Q: Can you give an example of a system where the internal energy is decreased by doing work on the surroundings?

A: Yes, a good example is a bicycle. When you pedal a bicycle, you are doing work on the surroundings (by turning the pedals) and the internal energy of the system (the bicycle) decreases.

Q: How does the internal energy of a system change when a system is compressed?

A: When a system is compressed, the internal energy of the system increases as the energy of the particles in the system increases.

Q: Can you think of any real-world examples where the internal energy of a system is increased by compressing the system?

A: Yes, a good example is a scuba tank. When a scuba tank is compressed, the internal energy of the system increases as the energy of the particles in the system increases.

Conclusion

In conclusion, the internal energy of a system is a fundamental concept in thermodynamics that plays a crucial role in understanding various physical processes. By understanding the factors that increase the internal energy of a system, we can better understand how systems behave and interact with their surroundings.

References

Cengel, Y. A., & Boles, M. A. (2015). Thermodynamics: An Engineering Approach. McGraw-Hill Education.
Kittel, C., & Kroemer, H. (1980). Thermal Physics. W.H. Freeman and Company.
Halliday, D., Resnick, R., & Walker, J. (2013). Fundamentals of Physics. John Wiley & Sons.