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The calorie is a unit of energy that originated from the caloric theory of heat. [ 1 ] [ 2 ] The large calorie , food calorie , dietary calorie , kilocalorie , 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 ).
The caloric theory is an obsolete ... In later combination with the law of energy conservation, the caloric theory still ... "A sketch for a history of early ...
A kilocalorie is the equivalent of 1000 calories or one dietary Calorie, which contains 4184 joules of energy.The notion that "a calorie is a calorie" is related to the idea that weight maintenance is a result of equalizing calorie input and calorie output, [4] and may lead to the practice of calorie restriction.
It was argued for some years whether energy was a substance (the caloric) or merely a physical quantity. [ citation needed ] The development of steam engines in the 18th century required engineers to develop concepts and formulas that would allow them to describe the mechanical and thermal efficiencies of their systems.
The history of thermodynamics is a fundamental strand in the history of physics, the history of chemistry, and the history of science in general. Due to the relevance of thermodynamics in much of science and technology, its history is finely woven with the developments of classical mechanics, quantum mechanics, magnetism, and chemical kinetics, to more distant applied fields such as ...
Food energy is chemical energy that animals (including humans) derive from their food to sustain their metabolism, including their muscular activity. [ 1 ] Most animals derive most of their energy from aerobic respiration , namely combining the carbohydrates , fats , and proteins with oxygen from air or dissolved in water . [ 2 ]
Energy intake is measured by the amount of calories consumed from food and fluids. [1] Energy intake is modulated by hunger, which is primarily regulated by the hypothalamus, [1] and choice, which is determined by the sets of brain structures that are responsible for stimulus control (i.e., operant conditioning and classical conditioning) and cognitive control of eating behavior.
Calorimetry requires that a reference material that changes temperature have known definite thermal constitutive properties. The classical rule, recognized by Clausius and Kelvin, is that the pressure exerted by the calorimetric material is fully and rapidly determined solely by its temperature and volume; this rule is for changes that do not involve phase change, such as melting of ice.