can you tell me anything about heat transfer or thermal energy?

Answer 1

Heat transfer is directly related to the kinetic energy transfer between objects. Lets say you had a hot piece of metal and some ice. When they make contact, the metal's molecules are moving rapidly and it bumps into the ice and transfers the movement to the ice. This results in the metal moving slower and the ice moving faster. The H2O will probably bump into another H2O molecule and more metal will transfer its kinetic energy to the water. As more and more H2O molecules move faster, the ice will melt and heat up.

So this is the essense of thermal energy and heat transfer... they involve moving molecules. With our eyes, we probably do not see the molecules moving but if you zoom in a whole lot, you can see lots of movement.

Answer 2

HEAT TRANSFER THROUGH MEDIUMS. SOLIDS R THE BEST CONDUCTORS OF HEAT. AMONG SOLIDS, METALS LIKE COPPER , ALUMINIUM ETC. R THE BEST CONDUCTORS . THERE R 3 PROCESSES IN WHICH HEAT IS TRANSFERRED - CONVECTION , CONDUCTION AND RADIATION.

U CAN GET FURTHER INFORMATION ABOUT THIS CHAPTER IF UR REFFERING SOME ENCYCLOPAEDIA SITES LIKE WIKIPEDIA.ORG

Answer 3

Sure, if you can be more specific, otherwise you get a diatribe of information that may or may not be relevant to your situation.

Answer 4

In thermal physics, heat transfer is the passage of thermal energy from a hot to a cold body. When a physical body, e.g. an object or fluid, is at a different temperature than its surroundings or another body, transfer of thermal energy, also known as heat transfer, occurs in such a way that the body and the surroundings reach thermal equilibrium. Heat transfer always occurs from a hot body to a cold one, a result of the second law of thermodynamics. Transfer of thermal energy occurs mainly through conduction, convection or radiation. Heat transfer can never be stopped; it can only be slowed down.

Heat transfer is of particular interest to engineers, who attempt to understand and control the flow of heat through the use of thermal insulation, heat exchangers, and other devices. Heat transfer is typically taught as an undergraduate subject in both chemical and mechanical engineering curriculums.

Conduction is the transfer of thermal energy through free electron diffusion or phonon vibration, without a flow of the material medium. In other words, heat is transferred by conduction when adjacent atoms vibrate against one another, or as electrons move from atom to atom. Conduction occurs mainly in solids, where atoms are in constant contact. In liquids and gases, the particles are further apart, giving a lower chance of particles colliding and passing on thermal energy.

Metals are the best conductors of thermal energy. This is due to the way that metals are chemically bonded: metallic bonds (as opposed to covalent or ionic bonds) have free-moving electrons and form a crystalline structure, greatly aiding in the transfer of thermal energy.

Fluids (liquids and gasses) are not typically good conductors. This is due to the large distance between atoms in a gas: fewer collisions between atoms means less conduction. As density decreases so does conduction. Conduction does not occur at all in a perfect vacuum.

To quantify the ease with which a particular medium conducts, engineers employ the thermal conductivity, also known as the conductivity constant or conduction coefficient, k. The main article on thermal conductivity defines k as "the quantity of heat, Q, transmitted in time t through a thickness L, in a direction normal to a surface of area A, due to a temperature difference ΔT [...]." Thermal conductivity is a material property that is primarily dependent on the medium's phase, temperature, density, and molecular bonding.


Convection is a combination of conduction and the transfer of thermal energy by circulation or movement of the hot particles to cooler areas in a material medium. This movement occurs from or to a fluid or within a fluid. In solids, molecules keep their relative position to such an extent that bulk movement or flow is inhibited.

Convection occurs in two forms: natural and forced convection.

In natural convection, fluid surrounding a heat source receives heat, becomes less dense and rises. The surrounding, cooler fluid then moves to replace it. This cooler fluid is then heated and the process continues, forming a convection current. The driving force for natural convection is buoyancy, a result of differences in fluid density when gravity or another body force is present.

Forced convection, by contrast, occurs when pumps, fans or other means are used to propel the fluid and create an artificially induced convection current. In some heat transfer systems, both natural and forced convection contribute significantly to the rate of heat transfer.

To calculate the rate of convection between an object and the surrounding fluid, engineers employ the heat transfer coefficient, h. Unlike the thermal conductivity, the heat transfer coefficient is not a material property. The heat transfer coefficient depends upon the geometry, fluid, temperature, velocity, and other characteristics of the system in which convection occurs. Therefore, the heat transfer coefficient must be derived or found experimentally for every system analyzed.

Radiation is transfer of heat through electromagnetic radiation in the heat spectrum. Hot or cold, all objects radiate heat—unless they are at absolute zero, which is unattainable. No medium is necessary for radiation to occur; radiation works even in and through a perfect vacuum. A prime example of this is the energy of the Sun, which travels through the vacuum of space before warming the earth.

Shiny materials typically reflect radiant heat, just as they reflect visible light; dark materials typically absorb heat, just as they absorb visible light. In actuality, light is another a form of electromagnetic radiation with a shorter wavelength (and therefore a higher frequency) than heat radiation. The difference between visible light and radiant heat is small: they are simply different "colors" of electromagnetic radiation.

Thermal energy has no generally agreed definition and the term will not usually be found in most dictionaries of physics or science. In everyday usage, thermal energy may be regarded either as 1. a synonym for thermodynamic energy (itself a synonym for internal energy) or as 2. a synonym for heat.

1. Seen as the internal energy of a system, there are two components to thermal energy. One component is the internal potential energy of the system - the energy the system contains at any moment due to the relative placement within the system of all its constituent parts. The second component is the internal kinetic energy of the system - the energy the system contains at any moment due to the relative motion within the system of all its constituent parts.

There may be a constant interchange within the system of internal potential energy and internal kinetic energy. However, in any thermodynamically isolated system the total thermal energy (the sum of the internal potential energy and the internal kinetic energy) remains constant.

In this context, the thermal energy of an ideal gas is only the sum of the kinetic energies of the idealised, volumeless particles which interact only with the walls of any container and not with each other so lack potential energy.

2. In the opinion of Whelan and Hodgson, authors of the classical A-level Physics reference text used for many years in the UK, thermal energy is to be preferred to "heat" when the latter is used as a noun: unless used rigorously starting from its traditional thermodynamic definition, its better to use "heat" loosely only as a verb. For example, it would be better to state that "if system A is at a higher temperature than system B, then, unless the two systems are thermally isolated from each other, thermal energy will flow from system A to system B. That is, system A will heat system B until the two systems are at the same temperature".