14-1 : Temperature and Thermal Energy

TemperatureTemperature

• The measure of the average kinetic energy of The measure of the average kinetic energy of the particles in a substance.the particles in a substance.

• Temperature is NOT energy.

Temperature

• If particles move faster, they have more kinetic energy and the substance has a higher temperature.

• Temperature is the same no matter how much matter you have.

3 Common Scales for measuring temperature:- Fahrenheit

• Water freezes at 32 and boils at 212

- Celsius• Water freezes at 0 and boils at 100

- Kelvin (subtract 273 from °C)• Water freezes at 273 and boils at 373

Absolute ZeroAbsolute Zero• Experiments have led Experiments have led scientists to conclude scientists to conclude that -273 that -273 °C ( 0 °C ( 0 Kelvin) is the lowest Kelvin) is the lowest temperature temperature possible.possible.

• At this temperature, At this temperature, no more energy can no more energy can be removed from be removed from matter.matter.

There are three scales used to measure temperature.

Kelvin

Celsius

Fahrenheit

Temperature is a measure of the average kinetic energy of the individual particles and Thermal Energy is the total energy of all the particles.

14-2 : The Nature of Heat

Heat

• Heat is the movement of Heat is the movement of thermalthermal energy energy from from one object to another.one object to another.

• Heat energy depends on the speed of the particles, the number of particles (the size or mass), and the type of particles in an object.

Heat Transfer• Heat always flows from the warmer substance Heat always flows from the warmer substance

to the cooler substance.to the cooler substance.

Heat Transfer-Radiation

• Radiation is the transfer of energy as electromagnetic waves– This energy causes the atmosphere’s

molecules to move faster which causes an increase in temperature.

– Examples:• Fire• The Sun

Heat Transfer-Conduction

• Conduction is the transfer of thermal energy from one material to another by direct contact.

Example:Example:–Touching something Touching something that is hotthat is hot–Putting a metal object Putting a metal object in a flamein a flame

Heat Transfer-Convection

• Convection is the transfer of thermal energy by the circulation or movement of a liquid or gas.– This circular motion is called a convection current

Examples:Examples:–Boiling waterBoiling water–WindWind

Conductors and Insulators

• Conductors conduct heat well.– Metals

• Insulators do not conduct heat well.– Wood, wool, straw, paper, cork, and some gases

such as air.

Specific Heat

• The amount of energy required to raise the temperature of 1 kilogram of a substance by 1 Kelvin.

Energy Conversions