HEAT

Activity

1. Rub your hands quickly against each other.

2. Then quickly place them onto your face.

3. Describe what you feel.

Your hands feel warm.

4. Why does it feel warm?

It feels warm as HEAT has been generated when we rubbed our hands together.

HEAT

Heat is a form of energy. Our main source of

HEAT on earth is the

SUN.

What are some sources of Heat?

Natural Sources Electrical Appliances Burning fuels like…

Volcanoes

Geysers

Lava from inside

the Earth.

Electric Iron

Light Bulb

Rice Cooker

Hair Dryer

Wood

Gas

Charcoal

Candle Wax

Petrol

Temperature is the measure of how hot or cold an object is.

Some HEAT sources are also sources of LIGHT. Eg. The

Light Bulb, It gives off both Heat & Light.

What are some Heat sources that are also Light sources?

Temperature is the measure of how hot or

cold an object is.

Temperature

An object that has a HIGHtemperature feels ______. An object that has a LOWtemperature feels ______.

hot

cold

The common units for temperature is

degree Celsius.

OC

Thermometers are used to give an accurate reading of temperature.

Thermometers come in many different types for different uses. For eg.

1. Laboratory Thermometers

2. Digital Thermometers

3. Pyrometers

Laboratory Thermometers

The temperature is

shown by the marking on

the thermometer which is

nearest to the mercury

level.

Are normally filled with

mercury or alcohol.

Laboratory thermometers

are used in the lab to

conduct experiments.

Digital Thermometers

PyrometersUsed to measure very high temperatures.

TemperatureHEAT

Differences

1. Is a form of energy.

2. Cannot be measured with a thermometer.

1. Is a measure of how hot or cold an object is.

2. Can be measured with a thermometer.

Heat Flows and Changes in Temperature

Basin filled with Warm Water

Cold can of Coke

What would happen to the can of Coke after it is

placed in the basin for a while?

The Coke can will slowly warm up until it

is the sametemperature as the water in the basin.

This is because it has gained heat from the

warm water.

Heat will always flow from the hotterobject to the colder object, until both

reach the same temperature.

Basin filled with crushed Ice.

Glass beaker filled with

hot coffee.

What would happen to the coffee in the beaker after it

is placed in the basin for a while?

Can you draw the arrows to show the flow of heat?

The coffee will slowly cool down until it is the same temperature as the ice in the basin.

This is as the coffee has lost heat to the ice.

When objects GAIN heat, they:

Increase in temperature.

Catch fire.

Change from solid to liquid. Eg. Ice melting.

Change from liquid to gas. Eg. Water boiling or evaporating.

Expand (Get Bigger, Increase in SIZE).

When objects Lose heat, they:

Decrease in temperature.

Change from gas to liquid. Eg. Condensation.

Change from liquid to solid. Eg. Water freezing to form ice.

Contract (Get smaller, Decrease in SIZE).

Beaker

Bunsen Burner

Boiling Water

Ice Cube

Good and bad conductors of Heat. (1)

Take a look at the experiment setup at the top of the page in your Text

Pg 129. Which of the candles will fall off first? Which will fall last?

What has happened: Heat has been conductedfrom the flame to the candles through the metal rod.

The candle that receives the conducted heat first will start to melt first.

Good and bad conductors of Heat (2).

Take a look at the experiment setup in your Text Pg 130. Which of the

toothpicks will fall off first? Which was the best conductor of heat?

What has happened: The metal rod is the bestconductor of Heat, it conducts heat fastest, so Toothpick A

will be the fastest to drop.

Air is the worst conductor, it conducts heat slowest, so

Toothpick C will drop last.

Good Conductors

SteelCopper

Iron

Tin Aluminium

Some examples of Good & Bad conductors.

Bad Conductors

PlasticWood

Clay

Glass

Frying Pan

Material?Steel

Material?Plastic

The handle of the frying pan is made of plastic as plastic is a poor conductor of

heat. This means that we can hold on to the handle while we are cooking.