Temperature and internal energy

Содержание и основные понятия

Temperature characterizes the body's thermal state, and internal energy consists of kinetic energy from the chaotic movement of particles and potential energy from their interaction.
GEF · Grade 8
PIF · Baseline
Interactive model
heat traffic
Temperature
Domestic energy
thermal equilibrium
01
The physical picture
What happens and what boundaries the model has.
Main message
Temperature characterizes the body's thermal state, and internal energy consists of kinetic energy from the chaotic movement of particles and potential energy from their interaction.
Warm motion does not stop even in a standing body.
Internal energy changes work or heat transfer.
The thermometer comes with the body in the heat balance and shows the temperature on the selected scale.
How to reason
First, name the system and the interaction, then select the values, and only then write down the law. The formula works within the model's assumptions.
02
Laws and values
Symbols should be read as a relationship of values, not as a recipe for substitution.
T
=
t
+
273
T=t+273
T
=
t
+
273
Kelvin and Celsius temperature connection
Δ
U
=
A
+
Q
\Delta U=A+Q
Δ
U
=
A
+
Q
Two ways to change internal energy
Review of the situation
When the palms are rubbed, mechanical work becomes internal energy: skin temperature rises without heat from the heater.
04
Links and application
In the real world
When the palms are rubbed, mechanical work becomes internal energy: skin temperature rises without heat from the heater.
Model verification
Compare the prediction with observation, evaluate the units, the order of magnitude and the influence of the factors not taken into account. Disparity does not always mean an error of law: often idealization is no longer sufficient.
C
What needs to be understood
Outcome 1
Explain the physical meaning of the topic "Temperature and internal energy" through the model, not just the formula.
Outcome 2
Diluting and correctly using terms: thermal motion, temperature, internal energy.
Outcome 3
Indicate the conditions for the applicability of the law, verify units and limit cases.
T
Terms of the topic
The definition should indicate the physical meaning, not a substitute for a domestic synonym.
heat traffic
Continuous chaotic movement of particles of a substance whose intensity is related to temperature.
Temperature
Physical value describing the thermal state of the system and the direction of spontaneous heat exchange.
Domestic energy
The sum of the kinetic energy of the chaotic movement of particles and the potential energy of their interaction.
thermal equilibrium
The condition in which the contacting systems have the same temperature and macroscopic heat exchange is stopped.
F
Origin and conclusion of the formulas
The fundamental law cannot be "proven" by algebras: for each record, it is stated whether it is a definition, an experimental law, or a model effect.
T
=
t
+
273
T=t+273
T
=
t
+
273
definition
Celvin temperature and celsius.
The following is an indication of the definition, experience or law from which this entry arises and where it is applicable.
0
∘
C
=
273,15
K
0\,^\circ\mathrm{C}=273{,}15\,\mathrm{K}
0
∘
C
=
273
,
15
K
Kelvin's class is injected with the same degree as the Celsius scale, but at the beginning with absolute zero.
T
=
t
+
273,15
≈
t
+
273
T=t+273{,}15\approx t+273
T
=
t
+
273
,
15
≈
t
+
273
So the scales are added to the temperature at Celsius; in school calculations 273.15 are rounded to 273.
Conditions:
Temperatures are expressed in calvins and degrees Celsius; recording with 273 is a school round and does not apply to temperature differences.
Monitoring:
The dimensions of both parts shall coincide; the result shall be checked for sign, order and limit case.
Δ
U
=
A
+
Q
\Delta U=A+Q
Δ
U
=
A
+
Q
Postulate or Model
Two ways to change internal energy.
The following is an indication of the definition, experience or law from which this entry arises and where it is applicable.
Q
>
0
,
A
>
0
Q>0,\quad A>0
Q
>
0
,
A
>
0
The first law of thermodynamics establishes an agreement: the heat transferred to the body and the work of external forces on the body increases its internal energy.
Δ
U
=
Q
+
A
\Delta U=Q+A
Δ
U
=
Q
+
A
The law of energy conservation requires that both transmission channels be folded; it's a physical postulate, not algebraic proof.
Conditions:
Locked thermodynamic system without change of macroscopic kinetic and potential energy; A means work on the system, Q positive when warmed up.
Monitoring:
The dimensions of both parts shall coincide; the result shall be checked for sign, order and limit case.
!
Model boundaries and typical errors
Error: Forget model condition
You can't put the formula on any situation just because it's a coincidence of letters. The key condition of this topic is that heat doesn't stop even in a standing body.
How to Check the Mind
Internal energy changes by work or heat transfer. Then check the units, vector direction and behaviour of the result at zero or very large parameter.
Σ
Conclusion on the topic
Temperature and internal energy
Temperature characterizes the body's thermal state, and internal energy consists of kinetic energy from the chaotic movement of particles and potential energy from their interaction.
Warm motion does not stop even in a standing body.
Internal energy changes work or heat transfer.
Any numerical result shall be accompanied by a unit, a sign and an explanation of its physical meaning.
The content is consistent with the FRP on Physics of the OS/OSS 2025 and the subject matter of the current lines of the PNP: I. M. Peryškin and co-authors (7–9), G. J. Mäkishev and coauthors (10–11), and with the lines "Engineers of the Future" and V. A. Kasyanov. The original texts are not reproduced, the text of the textbooks is not reproduced.