HEAT

What is heat?

Heat sources.

Conductive and insulating materials.

Measuring heat.

Heat effects.

LIGHT

Why do we see what is around us?

Kinds of objects according to the light.

Light colours

Mirrors

Lenses

SOUND

What is the sound?

Echo

HEAT

WHAT IS HEAT?

Atoms and molecules movements produce energy that we

call heat or thermic energy, which exists in all the matter.

The molecules in a hot body collide and move faster than in

a colder body.

http://www.indiana.edu/~oso/animations/energytransf

er.html

Remember from unit 5:

Everything around us is

made of matter. Matter is

formed by molecules.

Molecules are formed by

atoms.

MATTER

MOLECULES

ATOMS

HEATA body gets hot when it takes heat and cools down when

heat releases. Heat always goes from hot bodies to colder

bodies.

1 LITRE 1 LITRE 2 LITRES

19º 5º

5º+1º = 6º19º-1º = 18º

6º+1º = 7º18º-1º = 17º

7º+1º = 8º17º-1º = 16º

8º+1º = 9º16º-1º = 15º

9º+1º = 10º15º-1º = 14º

10º+1º = 11º14º-1º = 13º

11º+1º = 12º13º-1º = 12º

12º

Hot water

gives:Cold water

takes:

HEAT SOURCES

Heat sources are all the things we can get heat from.

Some heat sources are:

Wood, coal, gas… when they are burning.

Radiators, stoves… when they are working.

The Sun.

CONDUCTIVE AND INSULATING

MATERIALS

What happens if you put a sauce pan with boiling water and you

introduce a small part of a metal spoon and then you touch

another part of the spoon? Why does this happen?

What happens if instead of a metal spoon, you introduce a wood

spoon? Why does this happen?

HEAT

• There are some

materials that transmit

heat easily. These are

conductive materials.

• Other materials don´t let

heat go through them, for

example wood, plastic,

glass, clothe… These are

heat-insulating materials.

Heat is the only thing that

makes temperature rise or

fall. If we add heat,

temperature rises. If we

take heat away,

temperature falls.

There are high

temperatures when

molecules are moving and

vibrating quickly.

HEAT

MEASURING HEAT

To measure heat we use thermometers:

Clinic thermometer: it is the one

we use to measure our body

temperature. They can be

liquid-filled or electronic.

Environment thermometer: it is

the one we use to measure the

temperature of the air. Usually

alcohol-filled thermometers.

HEAT EFFECTS

OBJECTS TEMPERATURE CHANGES

When we take two objects with the same temperature and we put them together there

is no energy transfer between them.

But, when temperature is different there will be a temperature transfer from the hottest

object to the coldest until both of them get the same temperature.

10º 10º 10º

5º 15º 10º

HEAT EFFECTS

OBJECTS SIZE CHANGES

Heat changes objects size:

• With heat objects enlarge, heat causes objects to expand.

• When heat doesn´t affect objects they get smaller, they contract.

HEAT EFFECTS

MATTER STATE CHANGES

SOLID

LIQUID

GAS

LIQUID

LIGHT SOURCES

Natural: The Sun.

Artificial: The bulbs.

LIGHT

WHY DO WE SEE WHAT IS AROUND US?

We can see objects thanks to light. We see the light with

the sense of sight.

Light goes from the

place it is produced to

different objects that it

lights. The light

bounces on the

objects and gets into

our eyes.

Light propagates: it gets to

different objects even

though it comes from the

same source.

Most objects aren’t luminous. We need light to be

reflected on them to be able to see them.

KINDS OF OBJECTS ACCORDING TO THE LIGHT

TRANSPARENT: We can see objects that are behind them; they allow all the light to

pass through.

TRANSLUCENT: We cannot see objects behind them very clearly; they allow some

light to pass through.

OPAQUE: we cannot see objects through them; they do not allow light to pass

through.

TRANSLUCENT

TRANSPARENT

OPAQUE

The light we getfrom the Sun iscalled white lightand it is a mixtureof the sevencolours that formthe rainbow:

RedOrangeYellowGreenBlue

Indigo Violet.

LIGHT

LIGHT COLOURS

When light gets to an object that object can absorb orreflect different colours. The colour of the object is thecolour that it reflects.

We see bananas yellow

because they absorb all the

light colours but yellow.

We see snow white because it doesn´t absorb any

colour.

On the other side we see coal black because it absorbs

all the light colours.

LIGHT

White light decomposition

White light decomposes into the colours of the rainbow as it

goes through a glass prism.

LENSES

Lenses are pieces of glass that change the image of the objects we look at.

There are different kinds of lenses depending on the way they change the

image:

Lenses that let us see objects that are far away: telescopes and binoculars.

Lenses that let us see objects bigger than their actual size: magnifying

glasses and microscopes.

Lenses that improve our sight: glasses and contact lenses.

Lenses to capture images: cameras.

ECHO

Echo is produced when soundbounces on an object and goesback to its origin.

If you go to the mountains andyou speak loudly, sound willbounce on the mountains andthe it will go back to you.

SOUND

WHAT IS SOUND?

Sound are vibrations produced by objects; we perceive those vibrationsby the sense of hearing.

The sound of your voice vibrates the can and this causes the strings

to vibrate.

Sound needs a natural mean to propagate, as the air, the water or a stone. Sound cannotpropagate in vacuum, an empty space without air.

SOUND

As in the Moon there isno air, astronautscouldn´t hear thesound of a rocketbecause soundwouldn´t propagate tothem.