Chapter 6

THERMAL ENERGY

Temperature and Heat

Temperature- the average amount of kinetic energy of an object’s atoms or molecules

Thermal Energy- The sum of the KE and PE of the molecules in an object

Heat is thermal energy that flows from higher temperature to lower temperature

o Changes in thermal energy can be by mass times change in temperature times specific heat.

Q = (m) (ΔT) (C)o Measured in Joules

Specific Heat- the amount of heat needed to raise the temperature of 1 kg of a material 1 degree C

C = ΔQ/(m ΔT)

Measured in Joules / (kg°C)

o Specific Heat is a physical property of a material

Transferring Thermal Energy

Conduction

Convection

Radiation

Conduction

The transfer of heat by direct contact.

conductor - a material that transmits energy readily

example: metals

insulator - a material that does not transmit energy readily

Occurs in every state of matter, but solids are better conductors because of the closeness of the atoms.

ConvectionThe transfer of heat by the actual motion of a fluid (liquid or gas) in the form of currents.

won't work in solids…Why??? molecules are locked in place

Two types – natural and forced.

RadiationHeat transfer by electro-magnetic waves.

Light, UV rays, X-rays, & infrared rays.

Does not require matter.

Conduction/Convection/Radiation

Analogies

Conduction- passing a note from student to student

Convection- a student gets out of her/his seat and walks over and delivers the note to its recipient

Radiation- the first student tosses the note to its recipient