Sources of Energy
The usual convention in thermodynamics, work obtained from the system during the change regarded as positive where work is done on the system by an outside agency negative. For the more precise meaning of work and energy, we recall some relevant examples like oxidation or burning of coal or natural gas produces heat which ultimately enables the engine working. The mechanical work spent in rubbing two crystalline solid blocks of ice generates a large quantity of heat. Therefore there has an intimate relation between heat, and work, one can yield the other quantity. It is an extensive thermodynamics property like volume or surface area because it depends on the mass of the system. On the other hand, intensive properties like temperature, pressure, density, refractive index, etc are independent of the mass of the system.
Units of Heat or Work
Physical quantities like heat, potential or kinetic energy, and work describe or express in terms of base physical units or dimensions by multiplication or division. The units and dimensions of heat, various kinds of energy, or work can easily derive from the scientific definition or base mathematical formula. For example, work, W = F × s, where force (F) = maas × acceleration and acceleration = length sec-2. Hence, W = mass length2 sec-2. Therefore, the CGS and SI unit of work or heat = gm cm2 sec-2 or simply erg and kg m2 sec-2 or simply joule, another most used unit for energy is calories, kilocalories, eV, liter-atmosphere, etc.
Types of Energy Conversion
Heat is another kind of energy converted into all the other forms like electrical, chemical, mechanical, kinetic, or potential by producing work. But heat cannot be completely converted into work because any attempt to convert whole heat into work permanently changes the system or neighboring system. Another facts for learning chemistry or physics, when two objects with different temperatures come together, one with a higher temperature losses heat, and the other gains it.
The production or conversation of heat into work or energy going through a definite process, for example, when a liquid molecule freezes into solid yielding heat or water freezes into ice producing specific heat. Common examples for study heat energy conversation, redox reaction between chemical elements zinc and copper sulfate, expansion of stem, the glow of yellow phosphorus, combustion of petroleum fuel, or hydrocarbon. All the above types of examples, producing heat or work used for daily used energy for our environment and every system has within itself done some quantity of internal work in chemistry or physics.