Temperature March 6, 2014
What is temperature? • Measure of the average kinetic energy of the particles in an object • Can hot and cold be used to describe temperature? • No, how hot is hot and how cold is cold? • Hot and cold are relative terms, not true measurements of heat
How is temperature measured? • Science uses 3 different scales to measure the average kinetic energy • 1. Celsius – based on boiling and freezing points of water (0 and 100 degrees celsius) • 2. Fahrenheit – based on water freezing at 32 degrees and boiling at 212 degrees • 3. Kelvin – based on absolute zero, temperature at which all kinetic energy stops (-459F)
What happens to matter when it heats up? • Expansion – as matter is heated, the molecules begin to move more rapidly taking up more space • Use cracks in sidewalks and joints in bridges to allow expansion and contraction without breaking
How can expansion be useful at home? • Thermostats – use a metal (bimetallic strip) that expands when it heats up and turns on AC, when cool it contracts turning on the heat.
Conductors and insulators, what’s the difference? • Conductors – allow the flow of heat easily • Ex. Iron, steel, and aluminum • Helpful in cooking food or boiling water Insulators – prevent the flow of heat ex. Wood, plastic, cloth or ceramic Useful in moving hot objects without being burned