Thermal energy A common form of energy that is transmitted by conduction, radiation, or convection. Where heat is always transferred from a hot body to a cold one. The transfer of heat from one body to another causes its temperature to rise.^[1]

Thermal energy is the first thing a person knows about energy, regardless of whether or not he knows that sunlight is also a type of energy. The first man’s control of thermal energy by lighting fire was a major reason for the development of civilization. Until now, thermal energy plays an important daily role in our lives. We cook food with it, generate electricity from it in thermal stations, and use it to run engines such as the steam engine, the internal combustion engine, the jet engine, and missiles.

Thermal energy can be converted into any other type of energy, such as mechanical energy, as in a car, or electrical energy, as in an electric power station, or radiant energy, as in fire, stars, and others.^[2]

That is why thermal energy has been studied since ancient times, and its laws were formulated during the nineteenth century in what is called thermodynamics.

Thermal energy is measured in calories or joules.

define it[عدل]

know thermal energy E_th For a substance with the equation:

1. 
   $\displaystyle E_th=c\;\cdot m\;\cdot T\!$

   

Where:

c Specific heat,

m Bloc

T Absolute temperature, Kelvin.

When a substance gains heat, the kinetic energy of its molecules increases and appears in the form of thermal energy, and the body’s loss of heat decreases from the kinetic energy of its molecules. Thermal energy is kinetic energy, and that movement appears as a random movement of matter particles in gases and liquids, and a vibrational movement of the crystalline network of a solid and is transmitted by what is called a photon.

If the kinetic energy of all particles of a substance is equal to zero, then its temperature is at absolute zero in terms of mass m and specific heat c They don’t always go to zero. The temperature scale is Kelvin and is the reference for temperature scales such as Celsius or Fahrenheit. Absolute zero is -16 degrees Celsius and 273 degrees Celsius.

thermal balance[عدل]

If two systems of different temperatures are mixed, their temperature becomes equal through heat exchange. This equilibrium takes place by itself, and no heat can be transferred from a cold body to a hot body. This well-known phenomenon is defined in the second law of thermodynamics, which is one of the laws of thermodynamics. Heat transfer continues in the mixture until the temperature is equal in all its parts and it becomes in a state of thermal equilibrium. This process is called heat transfer.

The relationship between heat and temperature[عدل]

In our colloquial expressions, we call thermal energy heat and sometimes confuse it with temperature. For example, when the snow is heated, the snow gains heat in the form of heat of fusion without its temperature increasing. We see by observation that as long as there is ice with water, their temperature will be equal to zero degrees Celsius, and the snow will continue to gain heat and melt into water without the temperature of the mixture changing. This is because the heat content of ice is different from the heat content of water, and we say that the internal energy of the two is different. A process like this in which a system (ice) moves to another phase, water, is called a phase transition.

Another example of a phase transition is the boiling of water and the transition of water from a liquid state to a vapor (gaseous state). Also here, we find that water boils at 100 degrees Celsius and turns into steam without the water temperature rising above 100 degrees Celsius. During this process the water phase changes to the vapor phase, and the temperature of the steam does not rise until all the water has completely converted to steam. During the conversion of water into steam by gaining heat from heating, water acquires heat of evaporation and becomes steam.

These properties generally apply to most other substances such as alcohol, iron, copper, mercury, and others. Each of them has its specific heat, heat of fusion and heat of vaporization.

Suppose we have a piece of ice at -10°C and we heat it up. We find that the temperature of the snow gains heat at the rate of the specific heat of the snow, so the temperature of the snow gradually rises to -9, then -8, then -7 degrees Celsius until its temperature reaches zero degrees Celsius. Then the temperature is fixed at 0 degrees Celsius, and the ice acquires heat and gradually turns into water, while it acquires the heat of fusion. After it is completely melted into water and the heating continues, the temperature of the formed water begins to rise from zero by gaining the specific heat of the water. Until it reaches 100 degrees Celsius, it begins to boil and the water gains heat of evaporation, and the temperature of the water (and steam) remains at 100 degrees Celsius until all the water turns into steam, then with continued heating, the temperature of the steam rises as it acquires the specific heat of water vapor.

In gases, we sometimes talk about pressure energy, and this pressure energy is nothing but thermal energy. The gas molecules in a flask collide with each other due to their random thermal movement and collide with the wall of the flask. Part of the movement of the molecule in each shock is transmitted to the wall of the flask, and this is the pressure in the flask and we can measure it.

thermal energy and life[عدل]

Earth gets thermal energy from the sun. The sun is the mainstay of life on Earth. Several important factors for the emergence of life on Earth play here, including the Earth’s distance from the Sun (about 150 million km). This distance determines the average temperature on Earth by about 14 degrees Celsius over the seasons. If the earth was closer than that to the sun, the water would evaporate and the earth would leave into space, and the earth would become dry and unfit for life, like Al-Zahraa. And if the earth moved away from the sun, the temperature on the earth would decrease and it would also become unfit for life, as everything would freeze, and neither man nor animal would arise.

Humans, animals and plants depend on the energy of the sun’s heat. Plants store sunlight in the form of wood, carbohydrates, sugar, protein, oils and others through photosynthesis. When we feed on these substances, they provide us with the calories that our bodies need to carry out their vital activity and physical activity. This also applies to birds and animals.

In order for the human body to function and perform its vital activity, its body temperature must be 37 degrees Celsius. If it decreases a little or rises a little, it threatens human life. Calories are found in carbohydrates (such as starch and sugar), and in fats and proteins.

One gram of sugar, for example, generates heat in the body equivalent to 3.74 calories, 1 gram of fat generates about 9.4 calories, and one gram of starch generates 4.19 calories.

Thermal energy in an ideal gas[عدل]

Thermal energy is easy to define by looking at the state of an ideal gas. An ideal gas is a gas whose atoms are monomeric (not held together into molecules) at low pressure. Gas particles are considered to be very small point particles and that they do not affect each other, and only random collisions occur between them, filling the space in which they are present.

The kinetic energy of a single particle is given by the equation:

$\displaystyle E_kinetic=\tfrac 12mv^2\,\!$

Where:

m – his mass

v – It’s fast.

The thermal energy of a sample of gas is the number N of atoms is the sum of those energies of the atoms:

$\displaystyle U_thermal=\tfrac 12Nm\overline v^2=\tfrac 32NkT,$

Where the line above the velocity expresses the ‘average velocity’ of all the particles. The total thermal energy of the sample is directly proportional to the temperature T of the sample, and the proportionality constant represents the three directions in which the particle can move (up-down, right-left, forward-backward) and also represents the Boltzmann constant. The Boltzmann constant converts units between particles and the temperature of the sample as a whole. This mathematical formula leads directly to the ideal gas law, and it shows that internal energy U For an ideal gas its calorific energy consists of:

$\displaystyle U=U_thermal.\;$

[عدل]

See also[عدل]

• heat of fusion
• evaporation heat
• specific heat
• thermal conductivity
• Six degrees of freedom
• phase (matter)
• transformatively
• thermodynamic condition
• thermal movement
• ideal gas

Reference[عدل]

Thermal energy On sister projects:
	Pictures and audio from Commons. Books from Wikibooks.

• Physics portal
• energy portal

Retrieved from «https://en.wikipedia.org/w/index.php?title=thermal energy&oldid=60123324»