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The word energy derives from the Ancient Greek: ἐνέργεια, romanized: energeia, lit. 'activity, operation', [4] which possibly appears for the first time in the work of Aristotle in the 4th century BC. In contrast to the modern definition, energeia was a qualitative philosophical concept, broad enough to include ideas such as happiness ...
The energy value of coal, or fuel content, is the amount of potential energy coal contains that can be converted into heat. [1] This value can be calculated and compared with different grades of coal and other combustible materials, which produce different amounts of heat according to their grade.
This is an extended version of the energy density table from the main Energy density ... Reactor-grade uranium (3.5% U-235) in light-water reactor: 3,456,000: 35%: Pu ...
A new energy label, introduced in 2010, is based on the energy efficiency index (EEI), and has energy classes in the range A+++ to D. [11] The EEI is a measure of the annual electricity consumption, and includes energy consumed during power-off and standby modes, and the energy consumed in 220 washing cycles. For the washing cycles, a weighted ...
Energy efficiency was a lower priority when energy was cheap and awareness of its environmental impact was low. In 1975 the average fuel economy of a car in the US was under 15 miles per gallon [ 6 ] Incandescent light bulbs, which were the most common type until the late 20th century, waste 90% of their energy as heat, with only 10% converted ...
Energy quality is a measure of the ease with which a form of energy can be converted to useful work or to another form of energy: i.e. its content of thermodynamic free energy. A high quality form of energy has a high content of thermodynamic free energy, and therefore a high proportion of it can be converted to work; whereas with low quality ...
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4–5×10 4 J: Energy released by the combustion of 1 gram of gasoline [106] 5×10 4 J: Kinetic energy of 1 gram of matter moving at 10 km/s [107] 10 5 3×10 5 – 15×10 5 J: Kinetic energy of an automobile at highway speeds (1 to 5 tons [108] at 89 km/h or 55 mph) [109] 5×10 5 J Kinetic energy of 1 gram of a meteor hitting Earth [110]