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Thermal Energy and Heat. Thermal Heat and Matter. Heat – transfer of thermal energy from one object to another due to a difference in temperature Heat flows spontaneously from hot objects to cold objects Temperature – measure of how hot or cold something is. Thermal Heat and Matter.
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Thermal Heat and Matter • Heat – transfer of thermal energy from one object to another due to a difference in temperature • Heat flows spontaneously from hot objects to cold objects • Temperature – measure of how hot or cold something is
Thermal Heat and Matter • Thermal energy of an object depends on • Mass • Temperature • State of Matter (solid, liquid, gas)
Thermal Heat and Matter • Thermal contraction – volume of a material decreases due to a temperature decrease • Ex: A balloon will shrink when it is exposed to colder temperatures • Thermal expansion – volume of a material increases due to a temperature increase • Ex: A tupperware container will stretch and expand when put in the microwave
Specific Heat • Amount of heat needed to raise the temperature of 1 gram of material by 1o Celsius • Ex: You have 1 gram of water that is 50oC You want to raise its temp to 51oC The amount of heat needed to do this is called SPECIFIC HEAT
Specific Heat • Substances that heat quickly have a LOW specific heat • Ex: metals • Substances that heat slowly have a HIGH specific heat • Ex: wood, plastic, water
Heat and Thermodynamics • Conduction – thermal energy is transferred but matter is not transferred • Occurs within a material and between objects that are TOUCHING • Ex: The handle of a pan will gradually get hot when the pan is put on a hot burner • Heat transfers WITHIN the pan (from the bottom to the handle)
Heat and Thermodynamics • Convection – thermal energy is transferred when particles of a fluid (gas or liquid!) move from one place to another • Ex: ovens • Hot air in an oven rises and cool air in an oven goes back to the bottom
Heat and Thermodynamics • Radiation – energy is transferred by waves moving through space • Ex: Sun’s rays are waves of energy that move through space • All objects radiate energy • As an object’s temperature increases, rate of radiated energy increases