FORCES AND DISTORTIONS

Forces can distort some objects temporaly or permanently.

Elastic objects, such as a spring, return to their original shape when the force stops acting upon them. They are distorted temporaly.

Non-elastic objects, such as a piece of plasticine, remain permanently distorted when the force has stopped.

FORCES AND MOTION

Forces can affect motion in many different ways. They can:

-Make something move:for exemple, when you open a door, you push or pull to move the door.
-Stop a moving body:for example, when a basketball player catches a ball, the ball stops.
-Change the direction of a moving object: for exemple, when a tennis player hits a ball, it goes to the other side of the court.
-Increase the speed of a moving body: for exemple, the force a skateboarder uses to push the skateboard makes it go faster.
-Reduce the speed of a moving body:when the skateboarder puts both feet on the skateboard, the wheels rub against the ground and friction makes the skateboard go more slowly.

ACTIVITY FORCES AND MOTION

MATCH THE TWO HALVES OF EACH SENTENCE

1.Elastic objects                                            a.make something move.
2.Non-elastic objects                                    b.it stops.
3.Forces can                                                 c.are distorted temporaly
                                                                        by force.
4.When a tennis player hits a ball                   d.are permanently distorted
                                                                        by force
5.When a basketball player catches a ball      e.it changes direction.

FORCES

Forces are actions which make objects move, stop or change shape. They can be a push or a pull.

When you throw a ball, it moves. The movement is caused by the force you applied to the ball.

TYPES OF FORCES

There are different types of forces.
- GRAVITY. This force makes objects fall to the ground. If we throw an object into the air, gravity pulls it to the ground.

-ELECTRIC FORCE.This force is found between electrically charged objects. Electric force can attract or repel.

-MAGNETIC FORCE.This force affects magnets and some metallic objects. Magnetic force can attract or repel.

-FRICTION.When an object touches another object, it experiences a frictional force. This force acts in the direction opposite to the direction of movement. It slows or stops moving objects. For example, friction between a ball and the ground stops the ball rolling after a few metres.

ACTIVITY FORCES

Answer these questions:
1. What two forces can attract or repel?
2. What force makes objects fall to the ground?
3. Which force acts in the direction opposite to the direction of movement?

ACTIVITY MAGNETS AND MAGNETISM

1.An object which can attract other objects made of iron or mixtures of iron is called a ...
2. When the opposite poles of two magnets are placed together they...
3. When the same poles of two magnets are placed together they ...
4. The area around a magnet affected by magnetic forces is called a ...
5. A conducting wire wrapped around a piece of iron which acts as a magnet when an electrical current flows through the wire is called an ...