Heat Heat andand

Thermodynamics Thermodynamics

Rachel SandmanKristen Schlotman

Kiara SierraPhysics, period 6

Temperature

• Temperature tells how hot or cold something is.

• Three scales: Celsius, Fahrenheit, and Kelvin.

Heat and Internal Energy

• Heat always flows from higher temperature substances to lower temperature substances.

Measurement of Heat

• The units for heat are the calorie and the kilocalorie (1000 calories).

Specific Heat Capacity

• Different substances have different capacities for storing internal energy.

Thermal Expansion

• An increase in heat causes an expansion of the substance.

• An example is a thermostat’s bimetallic strip.

Conduction• Heat is

transferred through objects by conduction.

• Metals are the best conductors.

Insulation

• Insulators delay the transfer of heat.

• Liquids and gases in general are good insulators.

Convection

• Through convection, heating occurs by currents in a fluid.

Radiation• The sun’s heat is

transmitted through radiation.

• Energy transmitted by radiation is called radiant energy.

Newton’s Law of Cooling

• The rate of cooling of an object is approximately proportional to the temperature difference between the object and its surroundings.

Phase Changes• Evaporation (liquid to gas)• Condensation (gas to liquid)• Boiling (liquid to gas)• Freezing (liquid to solid)

First Law of Thermodynamics

• Whenever heat is added to a system, it transforms to an equal amount of some other form of energy.

Second Law of Thermodynamics

• Heat will never of itself flow from a cold object to a hot object.

Entropy

• Entropy is the measure of the amount of disorder.

• As disorder increases, entropy increases.