La température

Celsius, Fahrenheit, Kelvin, Réaumur and Rankine Temperature Conversion

The common scales for most temperature expressions are Celsius and Fahrenheit while Kelvin, Réaumur, and Rankine are used for specialized scientific applications.

The Celsius temperature scale is still sometimes referred as the "centigrade" scale. Centigrade means "consisting of or divided into 100 degrees" .
The Celsius scale, devised by Swedish Astronomer Anders Celsius (1701-1744) for scientific purposes, has 100 degrees between the freezing point of 0 degrees and boiling point of 100 degrees of pure water at sea level air pressure, 29.92 inches of mercury. That pressure criteria is often called an atmosphere, or more commonly, standard pressure.
The term Celsius was adopted in 1948 by an international conference on weights and measures. This is the most widely used scale in the world.

On the Fahrenheit scale, used primarily in the United States, the freezing point of water is 32 degrees and the boiling point is 212 degrees while measured at standard pressure. Zero degrees was the coldest temperature that the Greman born scientist Gabriel Daniel Fahrenheit (1686 -1736) could create with a mixture of ice and ordinary salt.
He is credited with the invention of the mercury thermometer and introduced it and his scale in 1714 in Holland, where he lived most of his life. His thermometer was based on the original design papers by Galileo for a temperatue and pressure measuring device.

In the formulas below, we use the mathematical standard computer conventions for algebraic and numeric expressions. The characters / represents division, * represents multiplication, - subtraction,
+ addition and = is equal. It is very important to follow the order of operations.

Tc = (5/9)*(Tf-32) ; Tc = temperature in degrees Celsius, Tf =  temperature in degrees Fahrenheit

For example, assume you have a Fahrenheit temperature of 98.6 degrees and you desire to convert it into degrees on the Celsius scale. Using the above formula, you would first subtract 32 from the Fahrenheit temperature and get 66.6 as a result. Then you multiply 66.6 by five-ninths and get the converted value of 37 degrees Celsius.

Tf = (9/5) *Tc+32 ; Tc = temperature in degrees Celsius, Tf =  temperature in degrees Fahrenheit

Assume that you have a Celsius scale temperature of 100 degrees and you wish to convert it into degrees on the Fahrenheit scale. Using the stated formula, you  first multiply  the Celsius scale temperature reading by nine-fifths and get a result of 180. Then add 32 to 180 and get final converted result of 212 degrees on the Fahrenheit scale.

Scientists use a third scale for unique measurements, called the absolute or Kelvin scale. This scale was invented by William Thomson (1824 -1907), also know as Lord Kelvin, a British scientist who made important decoveries about heat in the 1800's.
Scientists have determined that the coldest it can get, in theory, is minus 273.15 degrees Celsius. This temperature has never actually been reached, though scientists have come close. The value, minus 273.15 degrees Celsius, is called absolute zero. At his temperature, scientists believe that molecular motion would stop. You can't get any colder than that. The Kelvin scale uses this number as zero. To get other temperatures in the Kelvin scale, you add 273 degrees to the Celsius temperature. Conversion is very straight forward, though, strangely enough, the world degree is not used with the Kelvin scale.

A now somewhat obsolete scale is used in specific calculations and measurements. It was created by René Antoine Ferchault de Réaumur (1683-1757) a French scientist. He knew nothing of Fahrenheit's work ans did not use mercury, but did produce a good working thermometer. He used the freezing point of water as his zero mark, and put the boiling point at 80 degrees. This scale was widely used in the 18th and the 19th centuries, especially in France, in scientist communities. He has a greater claim to fame for much of the other scientific work he did.

William Rankine (1820-1872), a Scottish engineeer, created his scale, which was merely the Kelvin scale using the Fahrenheit degree instead of the Celsius. It has also had some wide use in scientific communities but is of no practical use in other areas of measurement.

Temperature Scale Ranges

°C : degree Celsius (centigrade), °Re : Réaumur, °F : degree Fahrenheit, K : Kelvin, °Ra : Rankine

à partir du texte proposé ci-dessus, répondre aux questions suivantes :

Quelles sont les différentes unités et leurs symboles ? (respecte l'ordre du texte)

        le degré ayant pour symbole , l'unité la plus utilisée dans le monde.

        le degré ayant pour symbole , unité utilisée principalement aux Etats-Unis.

        le ayant pour symbole , unité utilisée pour les applications scientifiques.

        le degré ayant pour symbole

        le degré ayant pour symbole                         

Quelle est l'origine de l'unité "degré Celsius" ? réponse de Blandine
Anders Celsius physicien astronome suédois (1701-1744)
100° d'écart entre la température de solidification de l'eau pure et sa température d'ébullition
échelle Celsius aussi appelée échelle centigrade

Tc =

                                  Tf =                           

Applications : (arrondir au dixième)

• si la température est 20°C, que vaut-elle en °F ?         
• si la température est 100°F, que vaut-elle en °C ?                                               

Quelles formules mathématiques existe-t-il entre la température en degrés Celsius et la température en Kelvin ? (respecte la typographie du texte)

Tc =

                                  Tk =                           

Qu'est-ce que le zéro absolu ? réponse de Blandine
O°K zéro absolu = - 273,15°C                température la plus basse que l'on puisse atteindre en théorie.