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The joule (/ dʒ uː l / JOOL, or / dʒ aʊ l / JOWL; symbol: J) is the unit of energy in the International System of Units (SI). [1] It is equal to the amount of work done when a force of one newton displaces a mass through a distance of one metre in the direction of that force.
The calorie is defined as the amount of thermal energy necessary to raise the temperature of one gram of water by 1 Celsius degree, from a temperature of 14.5 °C, at a pressure of 1 atm. For thermochemistry a calorie of 4.184 J is used, but other calories have also been defined, such as the International Steam Table calorie of 4.1868 J.
The centigrade heat unit (CHU) is the amount of heat required to raise the temperature of one pound (0.45 kg) of water by one Celsius degree. It is equal to 1.8 Btu or 1,899 joules. [26] In 1974, this unit was "still sometimes used" in the United Kingdom as an alternative to Btu. [27]
Note that the especially high molar values, as for paraffin, gasoline, water and ammonia, result from calculating specific heats in terms of moles of molecules. If specific heat is expressed per mole of atoms for these substances, none of the constant-volume values exceed, to any large extent, the theoretical Dulong–Petit limit of 25 J⋅mol ...
Joule estimated a mechanical equivalent of heat to be 819 ft•lbf/Btu (4.41 J/cal). The modern day definitions of heat, work, temperature, and energy all have connection to this experiment. In this arrangement of apparatus, it never happens that the process runs in reverse, with the water driving the paddles so as to raise the weight, not even ...
For example, the heat required to raise the temperature of 1 kg of water by 1 K is 4184 joules, so the specific heat capacity of water is 4184 J⋅kg −1 ⋅K −1. [3] Specific heat capacity often varies with temperature, and is different for each state of matter.
5. Water Makes Exercising Easier. If you’re on a weight loss journey, you might be trying to add some more physical activity to your day. Good for you.
In 1845, Joule published a paper entitled The Mechanical Equivalent of Heat, in which he specified a numerical value for the amount of mechanical work required to "produce a unit of heat", based on heat production by friction in the passage of electricity through a resistor and in the rotation of a paddle in a vat of water. [13]