Heat and balance of heat

Содержание и основные понятия

The amount of heat measures the energy transmitted by the heat transfer, which depends on the mass, temperature change and specific heat intensity of the substance for heating.
GEF · Grade 8
PIF · Baseline
Interactive model
heat
Specific thermal capacity
calorimeter
thermal balance
01
The physical picture
What happens and what boundaries the model has.
Main message
The amount of heat measures the energy transmitted by the heat transfer, which depends on the mass, temperature change and specific heat intensity of the substance for heating.
The specific heat capacity shows how much energy is needed to heat one kilogram of substance per Kelvin.
In an isolated system, the heat given and obtained is equal to the module.
The heat balance is applicable after the temperatures, masses and coefficients have been set to the agreed units.
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.
Q
=
c
m
(
t
2
−
t
1
)
Q=cm\left(t_2-t_1\right)
Q
=
c
m
(
t
2
​
−
t
1
​
)
heating or cooling
Q
отд
+
Q
пол
=
0
Q_{\text{отд}}+Q_{\text{пол}}=0
Q
Reverse
​
+
Q
Gender
​
=
0
Heat balance equation
Review of the situation
If hot water is mixed with cold without loss, the total temperature lies between the primary and is equal to the heat given and obtained.
04
Links and application
In the real world
If hot water is mixed with cold without loss, the total temperature lies between the primary and is equal to the heat given and obtained.
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 "Number of heat and balance" through the model, not just the formula.
Outcome 2
To distinguish and correctly use the terms: heat, specific heat, calorimeter.
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
Power transferred to or delivered to the system during heat transfer.
Specific thermal capacity
The amount of heat required to change the temperature of 1 kg of the substance by 1 K.
calorimeter
Heat-insulated heat exchange and heat measurement instrument.
thermal balance
Energy saving effect: In an isolated system, the amount of heat received and delivered is zero.
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.
Q
=
c
m
(
t
2
−
t
1
)
Q=cm\left(t_2-t_1\right)
Q
=
c
m
(
t
2
​
−
t
1
​
)
empirical law
Heating or cooling.
The following is an indication of the definition, experience or law from which this entry arises and where it is applicable.
Δ
t
=
t
2
−
t
1
\Delta t=t_2-t_1
Δ
t
=
t
2
​
−
t
1
​
Temperature change is equal to final temperature minus initial temperature.
Q
∼
m
Δ
t
Q\sim m\Delta t
Q
∼
m
Δ
t
Calorimetric tests determine the proportion of heat of mass and the variation of the temperature of the homogeneous body.
Q
=
c
m
(
t
2
−
t
1
)
Q=cm\left(t_2-t_1\right)
Q
=
c
m
(
t
2
​
−
t
1
​
)
The specific heat capacity c sets the amount of heat per kilogramme and one degree of temperature change.
Conditions:
No phase transition; c are considered permanent; Q refers to the body and positive at t2 > t1 according to the adopted sign.
Monitoring:
The dimensions of both parts shall coincide; the result shall be checked for sign, order and limit case.
Q
отд
+
Q
пол
=
0
Q_{\text{отд}}+Q_{\text{пол}}=0
Q
Reverse
​
+
Q
Gender
​
=
0
model effect
Equation of thermal balance.
The following is an indication of the definition, experience or law from which this entry arises and where it is applicable.
Δ
U
системы
=
0
\Delta U_{\text{системы}}=0
Δ
U
systems
​
=
0
In a thermally insulated system, the energy does not run out, so the sum of the changes in the internal energy of the members is zero.
Q
отд
<
0
,
Q
пол
>
0
Q_{\text{отд}}<0,\qquad Q_{\text{пол}}>0
Q
Reverse
​
<
0
,
Q
Gender
​
>
0
The heat given and received is attributed to the opposite signs.
Q
отд
+
Q
пол
=
0
Q_{\text{отд}}+Q_{\text{пол}}=0
Q
Reverse
​
+
Q
Gender
​
=
0
Energy conservation links the loss of hot bodies to the purchase of cold bodies.
Conditions:
The system is thermally insulated, and the work on external bodies is negligible; the thermal capacity of all bodies and calories as well as possible phase crossings are taken into account.
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 change the formula to any situation just because it's a coincidence of letters. The key condition of this topic is that the specific heat capacity shows how much energy it takes to heat one kilogram of substance per Kelvin.
How to Check the Mind
In an isolated system, the heat given and obtained is equal to the module. Then check the units, vector direction and behaviour of the result at zero or very large parameter.
Fuel combustion
When the fuel is fully burned, Q = qm is released, where q is the specific heat of combustion. In the heat balance, the energy actually obtained by the system is ~qm because the part is dispersed. The value of q depends on the composition and conditions of combustion; the formula does not describe the chemical kinetics and incomplete combustion.
Σ
Conclusion on the topic
Heat and balance of heat
The amount of heat measures the energy transmitted by the heat transfer, which depends on the mass, temperature change and specific heat intensity of the substance for heating.
The specific heat capacity shows how much energy is needed to heat one kilogram of substance per Kelvin.
In an isolated system, the heat given and obtained is equal to the module.
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.