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Normal human metabolism produces heat at a basal metabolic rate of around 80 watts. [1] During a bicycle race, an elite cyclist can produce around 440 watts of mechanical power over an hour and track cyclists in short bursts over 2500 watts; modern racing bicycles have greater than 95% mechanical efficiency. An adult of good fitness is more ...
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.
Basal metabolic rate (BMR) is the rate of energy expenditure per unit time by endothermic animals at rest. [1] It is reported in energy units per unit time ranging from watt (joule/second) to ml O 2 /min or joule per hour per kg body mass J/(h·kg).
Total emitted energy, , of a black body as a function of its temperature, . The upper (black) curve depicts the Stefan–Boltzmann law, M ∘ = σ T 4 {\displaystyle M^{\circ }=\sigma \,T^{4}} . The lower (blue) curve is total energy according to the Wien approximation , M W ∘ = M ∘ / ζ ( 4 ) ≈ 0.924 σ T 4 {\displaystyle M_{W}^{\circ ...
Conversely, we are normally in surroundings that are considerably cooler than the body's core temperature of 37 °C (98.6 °F) creating a gradient for thermal energy flow from the core to the surroundings. Therefore, the body must ensure it can also minimize the loss of heat to around 100 watts, if it is to maintain core temperature.
The metabolic equivalent of task (MET) is the objective measure of the ratio of the rate at which a person expends energy, relative to the mass of that person, while performing some specific physical activity compared to a reference, currently set by convention at an absolute 3.5 mL of oxygen per kg per minute, which is the energy expended when sitting quietly by a reference individual, chosen ...
Specific energy absorption rate (SAR) averaged over the whole body or over parts of the body, is defined as the rate at which energy is absorbed per unit mass of body tissue and is expressed in watts per kilogram (W/kg). Whole body SAR is a widely accepted measure for relating adverse thermal effects to RF exposure. [9]
When the body is black, the absorption is obvious: the amount of light absorbed is all the light that hits the surface. For a black body much bigger than the wavelength, the light energy absorbed at any wavelength λ per unit time is strictly proportional to the blackbody curve. This means that the blackbody curve is the amount of light energy ...