Hello! My name is Mary A. Johnson and I teach 7th grade Science at New Ellenton Middle School in New Ellenton, SC. I teach approximately 79 students throughout the day. We have been studying HEAT as a form of energy. The following page will help your students learn a little more about heat, it's history, heat transfer, and heat calculations.
HISTORY- In 1798 Benjamin Thompson, also known as Count Rumford, challenged the Caloric Theory. Caloric was known as an invisible weightless liquid whichflowed from hot to cold substances. Then J. Prescott Joule studied this theory and discoverd that heat and motion are related. His experiments supported the idea that objects in motion can produce heat. Scientists then concluded that heat is a form of energy caused by the internal motion of molecules of matter.
HEAT TRANSFER - There are three types of heat transfer: Convection which occurs when heat is transferred from one object to another through liquids and gases. An example of convection is the currents formed when cold air sinks and warm air rises.
Conduction occurs when heat is transferred through a substance by direct contact of the molecules. An example is when putting a metal spoon into a pot of hot liquid the spoon gets hot.
Radiation occurs when the sun's rays heat the Earth directly wiht infrared rays.
HEAT CALCULATIONS: You can measure heat in three different units: Degrees Farenheit, Degrees Celcius, and Kelvins.
Conversions are possible using the following methods: The formula C=5/9X(F-32). To convert Celcius to Kelvins add 273 and to convert Kelvin to Celcius subtract 273.
To calculate Heat Energy the following formula is used:
Heat gained or lost = mass X Change in Temp. X Specific Heat.
Note: The ability of a substance to absorb heat energy is it's specific heat.
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