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What Determines the Temperature of an Object? • Temperature is a measure of how hot or cold an object is compared to a reference point • BUT….. What causes an object to become hot or cold? • all moving objects contain kinetic energy, matter is made up tiny particles that are always moving. • As an object heats up, the particles inside move faster. As a result, the kinetic energy and the temperature increases
What Determines the Temperature of an Object? • The United States uses the Fahrenheit scale to measure temperature • Most countries use the Celsius scale • Scientist use the Kelvin scale (K) • The lowest measurement in Kelvin is 0 K, or absolute zero • K= 273 + °C
How is Thermal Energy Different from Temperature? • Different objects at the same temperature can have different amounts of energy • Temperature, thermal energy, and heat are closely related but are not the same thing • Thermal energy is the TOTAL ENERGY of all the particles in an object • The more particles an object has at a given temperature, the more thermal energy it has. • Also, the higher the temperature of an object, the more thermal energy it has
How is Thermal Energy Different from Temperature? An object’s thermal energy depends on its temperature and how many particles the object contains In the top two panels, which pie contains more thermal energy? How can these bottom pies have more thermal energy than the one of the left?
Heat • Objects do not contain heat… they contain thermal energy • Heat is the TRANSFER of thermal energy from a warmer object to a cooler object • The warmer object will cool down as the cooler object warms up until they are the same temperature.. At that moment heat stops transferring. • Heat is measured in units of energy: Joules (J)
How is Heat Transferred? Heat doesn’t transfer randomly. It only travels in one direction by three methods Conduction Convection Radiation Convection: type of heat transfer that only occurs in fluids (water and air) When air is heated, it rises above the cooler air. This causes a cycle Convection current. Convection current in the air causes wind and weather changes
Radiation: is the transfer of energy by electromagnetic waves. This is also the only form of heat transfer that does not require matter Conduction: transfers heat from one particle of matter to another within an object or between two objects http://www.youtube.com/watch?v=maPt__CZ1cY