Temperature Scales In Depth

The Farenheit scale is used by the Unitied States to define temperature. The common temperature points are 32 and 212 F To test a thermometer, distilled water is cruched into 1mm particles, is put into a beaker and filled with distilled water. The perfect scientific method is one which when the top of the ice pack is pushed down inside the beaker, the water braely rises to cover the ice pack. A saturated snow cone effect is what your are trying to create. On the Farenheit scale water boilos at 212. This value is affected by the changes in pressure from sea level to lets use Colorado as an example. To hard boil an egg in Los Angeles versus Denver results in a meal in LA before my friends up north.

The most commonly used temperature scale in the US today is the Farenheit scale, abbreviated F. In this scale, water freezes at 32 degrees and boils at 212 degrees. (This only holds strictly when atmospheric pressure equals the average sea level pressure. At high altitudes, water boils at a lower temperature, as anyone who cooks in the mountains knows.)

Centigrade (also called Celsius) scale Another common scale is the Centigrade (also called Celsius) scale. In this scale, water freezes at 0 degrees and boils at 100 degrees.

To convert between Farenheit and Celsius use this formula:
Farenheit Temperature = (Celsius Temperature)x(9/5) + 32

There are also temperature scales in which zero is absolute zero, the lowest possible temperature. (People have gotten close to absolute zero, but have never reached it. According to theory, we never will.) Absolute zero is at -273.15 C, or -459.67 F.

The Kelvin temperature scale uses the same size degree as Celsius, but has zero set to absolute zero. To convert from Celsius to Kelvin, add 273.15.

The Rankine temperature scale uses the same size degree as Farenheit. To convert from Farenheit to Rankine, add 459.67.

To convert from Kelvin to Rankine, multiply the Kelvin temperature by 9/5.

Here’s one example of temperature comparisons: 68 Farenheit is the same as 20 Celsius, 293.15 Kelvin, and 527.67 Rankine. For other comparisons, see the table below.

Absolute Zero

The first clue to the existence of absolute zero came from the expansion and contraction of gasses. We know that hot air rises and cold air falls. Air rises when it’s heated because it expands, so it’s less dense than the cooler air around it. It has bouyancy, just like a piece of wood in a pond, which floats because it’s less dense than the water. Air sinks when it cools because it contracts, so it’s more dense than the warmer air around it.

Suppose we took a certain amount of air and cooled it as much as we could. How much would it shrink? When scientists first began studying the behavior of of heated and cooled gasses, they didn’t have our modern cooling methods. They measured as best they could over the temperature range that they could reach. Then they plotted their data on graphs.

The graph of volume vs temperature for a sample of gas forms a straight line. (This assumes that you keep the pressure constant.) The lower the temperature, the smaller the volume. If you extend this line to low enough temperatures, it will eventually hit zero volume. Scientists noticed that, for all gasses, the temperature at which the graph said they would reach zero volume was about -273 C. This temperature became known as absolute zero, and is today the zero for the Kelvin and Rankine temperature scales. Nowadays, we know that gasses do not shrink to zero volume when cooled to absolute zero, because they condense into liquids at higher temperatures. However, absolute zero remains one of the basic concepts in cryognenics to this day. Although nothing can be colder than absolute zero, there are a few physical systems that can have what are called negative absolute temperatures. Oddly enough, such systems are hotter than those with positive temperatures!