2. FORCES
A force is something that changes an object's speed in
a given direction.
We can't see forces, but we can fell them and see the
effects they have on peopl or objet's.

3. PUSH AND PULL
Forces can be a push or a pull.
They can change an object's path and can also deform
objects.

4. CONTACT FORCES
Contact forces are transmitted through direct contact.

5. FRICTION
Friction is a special type of contact force.
Friction acts in the opposite direction of the movement.

6. MAGNETISM
Magnetism is the force of attraction or
repulsion caused by magnetic materials.This
force makes metalic objects move towards a
magnet.

7. GRAVITY
Gravity is a remote force of atraction.Every object that
has a mass exerts a gravitional force on other objects.
This gravitational force is directly proportional to the
objects mass: the force of attraction depends on the
mass of the object. A large object,l ike a planet or a
star,exerts a large gravitional force.

8. GRAVITY AND MASS
Gravity gives objects weight. The mass of an object is not the same as its
weight.
Weight is the force, that gravity can apply to an object. The more mass an
object has, the more gravity affects in.

9. MACHINES
We build machines to make work easier.There are two different types of
machines:simple machines and complex machines.

10. SIMPLE MACHINES
Simple machines are made of one or two main components.

11. COMPLEX MACHINES
Complex machines are
made up of many
components or simple
machines.

12. MACHINES HELP US
Machines help us perfom
many jobs. A harvester
can work a large area of
land.A lot people us to
cut the crops.Excavators
also help us dig large
holes in a short time.

13. COMMUNICATION
Communication is essential in
our society.Many machines
help us communicate.Before
these machines were invented
human beings could only use
oral and written
communication.

14. TELEGRAPH
In the 19 th century,the
telegraph allowed people
to send messages to distant
places.

15. COMPUTERS AND SATELITES
Nowadays computers
and satellites help us
communicate.

16. THE RADIO,TELEVISION AND
INTERNET
The radio,television and
Internet have changed the
way we interact and
communicate.

17. TRANSPORT
We need to travel and
transport cargo from
one place to another.

18. LAND TRANSPORT
Before the first cars
and lorries were
invented, people or
animals carried or
pulled cargo.

19. SEA TRANSPORT
Ancient boats used
wind power or the
strength of people
rowing to transpot
people and cargo by
sea.

20. AIR TRANSPORT
Transport experienced
a great change when
the first planes were
invented.

21. WRITERS: MIKEL B, MIKEL Z,
ALAIA AND AMAIA.