Translations of Encyclopedia about Physics

Quantity of Heat, Its Measurement, Thermodynamics

Mechanical work, executed by a certain object, requires internal energy. The existence of this energy depends solely on the internal state of the substance, made up of a thermodynamic system and which consists of a constant volume. It is also created from the kinetic energy of a system’s particles (kinetic energy), their mutual interaction, and partially also from the energy within their intermolecular particles (vibration energy).

Among other effects, adding energy to a system increases its temperature, which can be attributed to the increase of the system’s internal energy and the speeding up of the vibration of its internal particles.

To measure a change in temperature, we require an objective heat sensor: a thermometer. By rule, a liquid thermometer is used whose glass encasement uses a liquid whose volume changes in response to temperature changes, expanding in response to heat to indicate the temperature of its surroundings.

By rule, the liquid used most often in thermometers is mercury, which is very sensitive to changes in temperature. With an increase in temperature, the liquid expands to move up along the column within the sealed capillary. The height of the liquid level then marks the surrounding temperature. Temperature can be measured using different units.

Celsius	Fahrenheit	Kelvin
-20	-4	253
-10	14	263
0	32	273
10	50	283
20	68	293
30	86	303
40	104	313
50	122	323
60	140	333
70	158	343
80	176	353
90	194	363
100	212	373

Some important values in °C:

- 273,15 °C	Absolute zero; 0 kelvin
- 200 °C	Condensation of air
- 89 °C	Lowest temperature measured on the earth
0 °C	The temperature at which water freezes
58 °C	The highest natural temperature measured on the earth
100 °C	The boiling temperature of water
184 °C	The temperature at which paper lights on fire
1535 °C	The temperature at which iron melts
5530 °C	The temperature of the surface of the sun
30000 °C	The temperature at which lightning discharges

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