unit 5 forces and energy
TRANSCRIPT
FORCES AND MOVEMENT
What is force?Force is pushing and pulling things. This forces are called contact forces because they require touch.
PUSHING
PULLING
Contact forces can also stop things.
What do contact forces do?Contact forces can make an object start moving, stop moving, move faster, move slower or change direction.
The children apply a force to make their bicycles go
faster.
The dog applies a force to stop the
ball.
The crane applies a force to lift the car.
Contact forces can change the shape of some objects. They can also break them.
What do contact forces do?
Depending on the force applied and the material of the object, it...
…changes shape but returns to its original shape when the force
is removed.
…changes shape forever.
…breaks.
…doesn’t change shape.
What are magnetic forces?Magnets create magnetic forces. They are non-contact forces.
Magnets attract metallic objects and make them move without touching them.
There are natural magnets, like magntetite, and man-made magnets.
What do magnetic forces do?All magnets have 2 ends, called the north pole and the south pole.
If we put opposite poles of magnets together,
the attract each other.
If we put same poles of magnets together, they repel each other.
What are magnets used for?Many products of our daily life have magnets.
Magnets are used in watches.
A compass uses a magnet to find north.
Bank cards have a magnetic band.
What is gravity?Gravity is a non-contact force. It is a force of attraction that pulls all objects towards the centre of the Earth.
The Earth’s gravity stops us from floating away. It makes rain fall and keeps the water in the oceans.
What does gravity do?Because of gravity...
...we stay on the ground
...the apple falls on the boy’s head.
...everything that goes up comes back down.
...we can’t lift objects with a large mass.
As you move away from the Earth, the force of gravity is weaker. In space there is so little gravity that people and objects float!
What does gravity do?
http://www.youtube.com/watch?v=1v5gtOkyCG0
Can you cry on the space?
How do you wash your hair on the space?http://www.youtube.com/watch?v=kOIj7AgonHM
ENERGY
What is energy?Energy is the ability to do work. Any change needs energy.
All living things need energy to live. Machines and tools use energy to work.
Forms of energyThere are 6 main forms of energy:
MOTION ENERGY
SOUND ENERGY
ELECTRICAL ENERGY
CHEMICAL ENERGY
LIGHT ENERGY
HEAT ENERGY
There are 6 main forms of energy:Forms of energy
Which form of energy is this?Forms of energy
CHEMICAL ENERGY
LIGHT ENERGY
HEAT ENERGY
ELECTRICAL ENERGY
Which form of energy is this?Forms of energy
MOTION ENERGYLIGHT
ENERGYHEAT
ENERGY
SOUND ENERGY
Which form of energy is this?Forms of energy
MOTION ENERGY
SOUND ENERGY
The main sources of energyThe main sources of energy can be divided into 2 groups:
NON-RENEWABLE
RENEWABLE
COALPETROLEUMNATURAL GAS
SOLAR ENERGYHYDRO ENERGYWIND ENERGYBIOENERGY
Non-renewable energy sourcesThey are found under the ground.Because they are consumed very fast, they will run out.
PETROLEUM
COAL
NATURAL GAS
This energy sources are always available. They will never run out.
Renewable energy sources
SOLAR ENERGY
WIND ENERGY
HYDRO ENERGY
BIOMASS
Our lifestyle affect the amount of energy we use. To do this we must follow the 3 Rs:
How can we save energy?
REDUCE
REUSE
RECYCLE
