The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:
If the temperature of the body increases, the movements of molecules or atoms increase. These vibrations are then passed from one part of the body to the other. Measurement of the energy of which the molecules vibrate in a structure is referred to as heat contained in that object.
As per the concept of heat, it is defined as the movement of energy from a hot to a cooler object. The direction of the heat energy transfer is taken from the higher temperature material to the lower temperature substance. This is how the molecules vibrate faster and move their energy to the molecules that vibrate more slowly. Vibrational energy is often referred to as heat material. The heat content of the body renders it hot or cold.
A material can absorb heat without increasing the temperature by moving from one physical state to another. In the melting process, the substance is transformed from solid to liquid. In the step of sublimation, the solid is converted into a vapour state. The liquid is turned to steam in the boiling step.
Heat as a source of energy may be transformed into other sources of energy. E.g., heat is transformed into mechanical energy in motorised automobiles. It is converted to light energy in electrical lamps. It is eventually transformed into electrical energy in thermal power plants.
Convection is the transfer of heat energy by air and liquids. The particles move away from each other and are less compact as the air heats up and thereby allows the air to rise. When the colder air moves from below and heats up, and the cycle continues.
Radiation is the warming of the air by using heat waves that radiate out of the hot object in both directions before the other objects are absorbed. Heat transfer through radiation happens at the speed of light and covers long distances.
Conduction transfers heat from one material to another via direct contact. The moving molecules in a warm object will increase the energy of the molecules of a colder object. Solids are better heat conductors of heat than gases and liquids since the particles in solids are close together.
Specific heat (Csp) is the amount of heat needed to adjust the heat content of exactly 1 gram of material to exactly 1°C.
Specific values for heat can be calculated in the following way: If two materials, each originally at a different temperature, are in contact with each other, the heat always flows from the warmer material to the cooler material until all materials reach the same temperature. As per the law of energy conservation, the heat generated by the initially colder material must be equal to the heat lost by the initially warmer material.
We know that the temperature of an object changes as the heat energy is consumed. If the same amount of heat is given to equivalent masses of different substances, it is found that the temperature increase for each material is different. This is attributed to the fact that different compounds have different heat capacities. Therefore, the heat potential of a material is the amount of heat needed to increase the temperature of the entire substance by one degree. If the mass of the material is the unit, the heat capacity is called the specific heat capacity or the heat specific.
The formula for Heat Specific: Q = C m ∆t,
where Q = amount of heat consumed by the body;
m = body mass of the body;
∆t = temperature increase;
C = The specific heat capacity of a substance depends on the material type of the substance.
Latent heat is described as the heat or energy absorbed or emitted during the change of phase of the material. It could be either gas to a liquid or a liquid to a solid, and vice versa.
However, a significant observation we can remember with respect to latent heat is that the temperature of the material remains unchanged. As far as the mechanism is concerned, latent heat is the work required to resolve the attractive forces that bring molecules and atoms together in a material.
In this chapter, we learned about the concept of heat. We developed an understanding of heat and its related concepts like specific heat and latent. However, it is important to note that the increasing levels of heat in the atmosphere worldwide is the i = onset of many problems like the greenhouse effect and global warming.