Thermal EnergyHeat & Temperature

Definitions Energy

Can do work

Kinetic Energy Energy associated with the motion of

objects, large or small

Thermal Energy Kinetic energy of microscopic particles that

make up all matter

Definitions Heat

Total amount of thermal energy an object possesses

Flows from warmer to cooler objects(“Thermal energy in transit”)

Temperature Average thermal energy of

the molecules in a substance

DefinitionsObj A: Thermal Energy

Obj B: Thermal Energy

Obj A: Temperature

Obj B: Temperature

Heat: Energy Units Calorie – amount of heat needed to

change the temperature of 1 gram of water 1 ̊ C.

Joule – (1 calorie = 4.18 joules)

NOTE: Food calories

Temperature Scales

Celsius ( ̊ C ): Our unit of choice Kelvin ( K ): Based on “absolute

zero” Farenheit ( ̊ F ): Silly imperial

unit

Temperature ScalesCelsius ( ̊ C )

Kelvin ( K )

Farenheit ( ̊ F )

Water Boils 100 373 212

Water Freezes 0 273 32

“Absolute Zero”

-275 0 -459

Room Temperature

20 293 68

Specific Heat Capacity Quantity of heat required to change the

temperature of a unit mass of the substance by one degree.

Measure of a substance’s ability to “store” thermal energy.

Laws of Thermodynamics Whenever heat flows into or out of a

system, the gain or loss of thermal energy equals the amount of heat transferred.

Heat never spontaneously flows from a cold substance to a hot substance.

No system can reach absolute zero.

Kinetic Molecular Theory All matter is made up of tiny particles.

These particles are in constant motion.

Increasing the motion of the particles increases temperature.

Thermal Expansion As a substance is heated (thermal energy is

increased), particles move faster and farther apart. Liquids expand more than solids with increases in

temperature. Gases expand more than liquids with increases in

temperature.

Definitions Kinetic energy is a general term describing the energy

associated with the motion of objects (large or small objects). You can calculate the kinetic energy of an object of mass m with a velocity (speed) v from the formula K.E. = 1/2 mv^2. Thermal energy refers to the kinetic energy of the microscopic particles (atoms and molecules) that make up all samples of matter - i.e. all objects. When you add heat to an object, you increase the temperature of the object (usually) and that heat increases the kinetic energy of the molecules that comprise that object. In fact, temperature is a measure of the average kinetic energy of the microscopic particles that make up an object.