Thermal Energy and Heat

Thermal Energy and Matter

• Heat – transfer of thermal energy from one object to another because of temp. difference

• Heat flows spontaneously from hot objects to cold objects

• Temperature – measure of how hot or cold an object is compared to a ref. pt.– Related to avg. KE of the particles in an

object due to their random motion through space

• Thermal energy – total PE and KE of all the particles in an object

• Thermal contraction – when the volume of a material decreases due to a decrease in temperature

• Thermal Expansion – increase in the volume of a material due to increase in temp.

• Specific heat – amt. of heat needed to raise the temp. of 1g of a material by 1 degree Celsius

Heat and Thermodynamics

• Conduction – transfer of thermal energy with no overall transfer of matter– Occurs within a material or between materials that are

touching– Occurs slower in gases than in liquids or solids

• Thermal Conductor – material that conducts thermal energy well

• Thermal insulators – poor conductor of thermal energy

Convection

• Convection – transfer of thermal energy when particles of a fluid move from one place to another

• Convection currents – occur when a fluid circulates in a loop as it alternately heats up and cools down– Important in many natural cycles such as

ocean currents, weather systems, and movements of hot rock in Earth’s interior

• Radiation – transfer of energy by waves moving through space– All objects radiate energy– Rate at which energy radiates increases with

temp.