Thermodynamics Conceptual Question

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SUMMARY

The discussion centers on the relationship between energy addition, internal energy, and temperature in thermodynamics. When energy is added to a system without changes in kinetic or potential energy, the temperature of the system typically rises. This is due to the increase in internal energy, which comprises bond energy and thermal energy. The participants confirm that an increase in volume, which is proportional to temperature, supports this conclusion.

PREREQUISITES
  • Understanding of thermodynamic principles, specifically internal energy and temperature relationships.
  • Familiarity with the concepts of kinetic and potential energy in a macroscale context.
  • Knowledge of the equations governing thermodynamics, such as Internal Energy = Bond energy + Thermal energy.
  • Basic grasp of the relationship between volume and temperature in thermodynamic systems.
NEXT STEPS
  • Study the laws of thermodynamics, focusing on the first law and its implications for internal energy.
  • Explore the concept of thermal energy and its role in temperature changes within a system.
  • Learn about the relationship between volume and temperature in ideal gases and real systems.
  • Investigate the implications of energy transfer in closed systems and its effects on internal energy.
USEFUL FOR

Students of thermodynamics, educators teaching thermodynamic principles, and professionals in physics or engineering fields seeking to deepen their understanding of energy dynamics in systems.

fridakahlo
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Hi! I'm new to the forums, so I apologize in advance if I'm posting my question in the wrong section. I'm studying thermodynamics right now, and I came across this sentence from my book:

Homework Statement


"When energy is added to a system and there is no change in the kinetic or potential energy of the system, the temperature of the system usually rises."

Homework Equations


Volume is proportional to Temperature
Internal Energy= Bond energy + Thermal energy

The Attempt at a Solution


I'm confused. Wouldn't adding energy to the system increase the system's internal energy (therefore inc. its kinetic/potential energy)? The only way I can see the above statement to be true is if there was an increase in volume of the system. And since volume is proportional to temperature, the temperature of the system would also rise. Are my assumptions correct or am I overthinking it? :oldconfused:
 
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fridakahlo said:
Hi! I'm new to the forums, so I apologize in advance if I'm posting my question in the wrong section. I'm studying thermodynamics right now, and I came across this sentence from my book:

Homework Statement


"When energy is added to a system and there is no change in the kinetic or potential energy of the system, the temperature of the system usually rises."

Homework Equations


Volume is proportional to Temperature
Internal Energy= Bond energy + Thermal energy

The Attempt at a Solution


I'm confused. Wouldn't adding energy to the system increase the system's internal energy (therefore inc. its kinetic/potential energy)? The only way I can see the above statement to be true is if there was an increase in volume of the system. And since volume is proportional to temperature, the temperature of the system would also rise. Are my assumptions correct or am I overthinking it? :oldconfused:
In this context, when they are talking about kinetic or potential energy, they are referring to the macroscale. The potential energy they are referring to is gravitational potential energy, and the kinetic energy they are referring to is based on the mass average velocity over each small localized volume including a huge number of molecules.

Your interpretation that the internal energy increases and the temperature increases is totally correct.
 
Thanks Chestermiller!
 
Last edited:

Thread 'Magnitude of buoyant force in fluids of different densities'

The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?
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