4th grade. Forces, matter and materials.

Forces, matter and material.... our new unit...

Forces is a push or pull which acts on an object and as a result of this interaction there is a change of motion in the object.

Effect of forces: forces can make an object

- move
- stop
- speed up
- slow down
- change direction
- change shape

Types of forces:

1.- Non-contact forces: a force that affects objects without touching them. There is no direct contact with the object.
-Gravity: is a force that attract objects toward each other.
Isaac Newton was the first person to identify this force while sitting under an apple tree. Imagen relacionada

-Magnetism: is a force that attract of repulse objects caused by a magnetic material.

Magnets have two poles: north and south pole
If we put north pole with north pole the magnets repel
If we put north pole with south pole, the magnets attract.

-Electrostatic: is the force cause by a charged body towards another charged body.

2.- Contact forces: a force that affects objects when it touches them
- Friction: is the force that exists when two objects rub against each other. This acts in the opposite direction to the direction of the movement.

-Muscular force: it is the force produced by the action of muscles.

-Bouyancy force: it is the force produced by the opposite direction

Let's take a look at this group's Power Point.

Matter:is anything that takes up space and has a mass.
Matter makes up any materials.
Matter has three states
Solid
Liquid
Gas

Physical properties of matter
Hardness: hard,strong, weak.. can it bend easily??
Size: big, small, long, short, thin, thick....
Texture: rough, soft, smooth, pointy, hard
Odor: stinky, sweet,smelly, fresh,
Taste : sour, sweet, salty, spicy
Shape: square, rectangle, triangle, oval,....

Mass is the amount of matter in an object. We can measure mass in grams, kg.

Volume: is the amount of space that something occupies. We measure volume in ml, liters.

Gases: do not have a shape nor volume
Liquids: do not have a shape, but they have a volume.
Solids: they have shape and volume.

Density: is the quantity of material, mass, in a certain place or volume. this is calculated dividing the mass by its volume (kg/l)

Now we will look at the different materials. Check all these materials used in a car.....

Steel: is a strong metal, that protects you if there is an accident.
Aluminium: it is a strong metal too, but lighter and easy to work.
Plastic: is a stron, light and long lasting material. It is also very cheap. It is made from oil.
Glass: is a transparent material used for windows. It also protects the people in the car. It is made from sand.
Rubber: is a flexible and long -lasting materials.
Wood: is a strong natural material.
Fabric: is a material made from wool, cotton,....
Paper: it is a natural material made from wood.

Some materials and natural, such as: wood, oil, sand
others are manufactured: paper, glass, plastic...