Temperature and Heat: page 73

QUESTION: Why do objects get cold?

OBJECTIVE: SWBAT explain the difference between temperature and heat.

VOCABULARY: temperature absolute zero heatconduction convection radiation

Temperature and Heat

Write these questions onto page 73

1. What are the three temperature scales?

2. What’s the coldest possible temperature?

3. What direction does heat travel?

Temperature We typically think of temperature as how hot or cold an object feels. Temperature actually measures how fast molecules are moving.

Temperature can be measured on three different temperature scales, Fahrenheit, Celsius and Kelvin.

A thermometer is used to measure temperature.

Celsius ScaleCelsius is the temperature scale based on the metric system and used by the rest of the world.

On this scale water boils at 100°C

On this scale absolute zero at -273°C

On this scale water freezes at 0°C

Fahrenheit ScaleFahrenheit is the temperature scale used in the United States.

On this scale water boils at 212°F

On this scale water freezes at 32°F

On this scale absolute zero at -459°F

Kelvin ScaleKelvin is the temperature scale used by physical scientists.

On this scale water boils at 373°K

On this scale water freezes at 273°K

Absolute Zero 0°K

Comparing ScalesHere is a comparison of all three temperature scales.

Absolute ZeroAbsolute zero (0°K) is the coldest possible temperature.

At this temperature the particles in an object stop to move.

At absolute zero matter has no kinetic energy.

Heat Heat is the movement of thermal energy from warmer objects to colder ones.

Getting Cold?

You really don’t get cold, you lose heat. Nature tries to keep things balanced and equal. When you hold an ice cube, the heat leaves your hand and warms (melts) the ice. The loss of heat by your hand makes you feel cold.

Heat Transfer Heat can move to another object in three different ways.

Conduction

Convection

Radiation

CONDUCTION

Heat causes the molecules to wiggle (vibrate) faster and faster. This motion is transferred from molecule to molecule through the piece of matter. The heat travels from one end of the object to the other end.

This type of heat transfer

happens between solids

that are touching.

CONVECTION

This type of heat transfer happens

between liquids and gasses.The molecules not only wiggle (vibrate), but they change their location.

Hot matter rises and cold matter sinks. As the matter being heated rises it is replaced by colder matter that is sinking. This causes the circular motion that always happens during convection.

RADIATION

This type of heat transfer happens without any matter touching.

Heat waves carry the energy

across empty space.

Heat waves do not need matter to travel. Radiation is the type of heat transfer that happens when flames and the Sun heat other objects.

Heat Transfer Quiz

On page 73 of your notebook, number 1 through 5 and answer the following questions.

ANSWERS

1. Conduction2. Radiation3. Conduction4. Conduction5. Convection or Radiation

Put the number from the list below in the correct space.

Freezing water

Boiling water 100

320

7020

98.637

212

Body temp.

Room temp.

Temperature and Heat: page 73

Be sure you have answered these questions.

1. What are the three temperature scales?

2. What’s the coldest possible temperature?

3. What direction does heat travel?

VOCABULARYTemperature- the average kinetic energy of the particles in an object

Absolute zero- the coldest temperature. Particles in the object stop moving.

Heat- the movement of thermal energy from high to low.

conduction– the transfer of heat between solids that are touching.

convection– the transfer of heat through the movement of fluids.

radiation– the transfer of heat through space.