# What is temperature? Part 1

By Gabe L.
What is Temperature?
Temperature is a measurement of heat and coolness. In America, we use Fahrenheit. In most other countries the metric system based Celsius is used. Fahrenheit is based on 32 degrees, when water freezes and 212 degrees, when water boils. Celsius is based on 0 degrees, when water freezes, and 100 degrees, when water boils. In the 1970s, there was an effort to make Celsius the common measurement in the United States, but the conservative Americans resisted the change and Fahrenheit remains the standard in the U.S.

A thermometer is used to measure temperature. The liquid used inside a thermometer used to be mercury, a liquid metal. Now alcohol is used. This is how a thermometer works. There are molecules at the bottom part of the thermometer. As the temperature gets higher the molecules create energy and force the liquid to go up.

Figure 1. This is a diagram showing a thermometer and its parts.

How Temperature Was Invented
The thermometer was created by Galileo around 1600. This marked the beginning of the scientific study of heat. Early scientists faced great challenges in establishing “fixed points” with the thermometer, such as the boiling and freezing points of water. It took 90 years after Galileo invented the thermometer for boiling and freezing to be recognized. By the mid-1700s the Swedish astronomer, Andres Celsius, helped create an agreement among scientists that the boiling and freezing of water were the best fixed points on the thermometer.

Figure 2. Three measurements of temperature. Image retrieved from: http://www.google.com/search?um=1&hl=en&biw=1280&bih=680&tbm=isch&btnG=Search&oq=how+was+temperature+invented++image&aq=f&aqi=&gs_upl=18824l33374l0l36096l48l32l0l0l0l1l990l2983l3-1.2.1.1l5l0&q=how%20was%20temperature%20invented%20image

Effect of Temperature on Matter
The energy of all the particles in a sample of matter is called thermal energy. When a warm object is brought near a cooler object thermal energy is transferred from the warmer object to the cooler object. This is called heat. When an object is heated it gains thermal energy, its particles move faster, and its temperature rises. When matter is cooled, it loses thermal energy, which causes its particles to move more slowly and its temperature to drop.
What happens to water at different temperatures provides a very good example of the effect of heat upon matter. When the temperature of water is very cold (Below 0 c) the water freezes and the particle’s become solid ice. When the temperature of the water is raised the particles speed up and become a liquid. If the temperature of the water is raised further the particles move even faster and turn into steam, which is a gas form of water. This is true with almost every tipe of matter, but the freezing and boiling point are different.

Figure 3. A thermometer with Fahrenheit and Celsius measurments. Retrieved from:http://www.google.com/search?hl=en&sugexp=pfwc&cp=7&gs_id=k&xhr=t&q=thermometer&gs_sm=&gs_upl=&bav=on.2,or.r_gc.r_pw.&biw=1280&bih=680&wrapid=tljp1316741303460012&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi

References
Chang, Hasok. Inventing Temperature. Oxford: Oxford University Press, 2004.
"Celsius temperature scale." Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica, 2011. Web. 22 Sep. 2011.
“What is the Celsius temperature scale?’ Discovery Channel, 2011. Web. 22 Sep. 2011.
National Geographic Society. The Nature Of Matter. NY, NY, 2002