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The term "thermal energy" is often used ambiguously in physics and engineering. [1] It can denote several different physical concepts, including: Internal energy: The energy contained within a body of matter or radiation, excluding the potential energy of the whole system, and excluding the kinetic energy of the system moving as a whole.
Origins of heat and cold adaptations can be explained by climatic adaptation. [16] [17] Ambient air temperature affects how much energy investment the human body must make. The temperature that requires the least amount of energy investment is 21 °C (70 °F). [5] [disputed – discuss] The body controls its temperature through the hypothalamus.
As in other mammals, human thermoregulation is an important aspect of homeostasis. In thermoregulation, body heat is generated mostly in the deep organs, especially the liver, brain, and heart, and in contraction of skeletal muscles. [1] Humans have been able to adapt to a great diversity of climates, including hot humid and hot arid.
This creates a limit to the amount of heat energy that can do work in a cyclic process, a limit called the available energy. Mechanical and other forms of energy can be transformed in the other direction into thermal energy without such limitations. [14] The total energy of a system can be calculated by adding up all forms of energy in the system.
The calorie is a unit of energy that originated from the caloric theory of heat. [1] [2] The large calorie, food calorie, dietary calorie, or kilogram calorie is defined as the amount of heat needed to raise the temperature of one liter of water by one degree Celsius (or one kelvin).
According to energy conservation and energy being a state function that does not change over a full cycle, the work from a heat engine over a full cycle is equal to the net heat, i.e. the sum of the heat put into the system at high temperature, q H > 0, and the waste heat given off at the low temperature, q C < 0.
The operative temperature, which is a more functional measure of thermal comfort in a building, is calculated from air temperature, mean radiant temperature and air speed. [6] Maintaining a balance between the operative temperature and the mean radiant temperature can create a more comfortable space. [7]
This is a list of units of measurement based on human body parts or the attributes and abilities of humans (anthropometric units). It does not include derived units further unless they are also themselves human-based. These units are thus considered to be human scale and anthropocentric.