Thermodynamics Conceptual Question

Click For Summary
The discussion revolves around a thermodynamics question regarding the relationship between added energy, internal energy, and temperature. The original poster is confused about how adding energy can increase temperature without affecting kinetic or potential energy, leading to a clarification about the definitions of kinetic and potential energy at the macroscale. It is confirmed that adding energy does indeed increase internal energy, which in turn raises temperature. The connection between volume and temperature is also acknowledged, reinforcing that an increase in volume can contribute to temperature rise. Overall, the poster's understanding is validated, emphasizing the correct interpretation of thermodynamic principles.
fridakahlo
Messages
10
Reaction score
1
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:
 
Physics news on Phys.org
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 'Coulomb's force vs the Lorentz force'

Beams of electrons and protons move parallel to each other in the same direction. They ______. a. attract each other. b. repel each other. c. neither attract nor repel. d. the force of attraction or repulsion depends upon the speed of the beams. This is a previous-year-question of CBSE Board 2023. The answer key marks (b) as the right option. I want to know why we are ignoring Coulomb's force?
View full post »
Thread 'Struggling to make relation between elastic force and height'

Thread 'Struggling to make relation between elastic force and height'

Hello guys this is what I tried so far. I used the UTS to calculate the force it needs when the rope tears. My idea was to make a relationship/ function that would give me the force depending on height. Yeah i couldnt find a way to solve it. I also thought about how I could use hooks law (how it was given to me in my script) with the thought of instead of having two part of a rope id have one singular rope from the middle to the top where I could find the difference in height. But the...
View full post »

Thread 'Speed of moth related to Doppler Effect'

I treat this question as two cases of Doppler effect. (1) When the sound wave travels from bat to moth Speed of sound = 222 x 1.5 = 333 m/s Frequency received by moth: $$f_1=\frac{333+v}{333}\times 222$$ (2) When the sound wave is reflected from moth back to bat Frequency received by bat (moth as source and bat as observer): $$f_2=\frac{333}{333-v}\times f_1$$ $$230.3=\frac{333}{333-v}\times \frac{333+v}{333}\times 222$$ Solving this equation, I get ##v=6.1## m/s but the answer key is...
View full post »

Similar threads

Additivity of thermodynamic potentials?
Replies
1
Views
503
Heat added to system increases mass
Replies
12
Views
1K
Thermodynamics: Internal Energy, Heat and Work Problem
Replies
1
Views
2K
Temperature & Gas: Correct or Incorrect?
Replies
12
Views
2K
Isothermal, isobaric and adiabatic
Replies
6
Views
2K
Can heat flow into a body without increasing the mean kinetic energy?
Replies
1
Views
1K
Entropy and the Laws of Thermodynamics
Replies
3
Views
2K
Correct statement about internal energy
Replies
25
Views
4K
Why is temperature constant after gas has expanded?
Replies
33
Views
2K
What Happens When Gas Expands at Constant Pressure?
Replies
12
Views
6K