1. Alkarma Language School Friction ____________________ What is friction?

2. Alkarma Language School Friction It is a force that slows down the moving object & has its effect in the opposite direction of the object's movement.

3. Alkarma Language School 1)- Rough surface ( friction force increases & motion force decreases) Friction force depends on the type of material.

4. Alkarma Language School 2)-Smooth surface ( friction force decreases & motion force increases) Friction force depends on the type of material.

5. Alkarma Language School Types of friction force: 1)- Friction force in solids. 2)- Air resistance. 3)- Water resistance.

6. Alkarma Language School 1)- Friction force in solids

7. Alkarma Language School 2)- Air resistance It is a type of friction force resulting from object movement on air. Rockets, Aircrafts & planes are designed in stream line to reduce the air resistance (friction force)

8. Alkarma Language School 3)- Water resistance It is a type of friction force resulting from object movement in water. The fish body and ship body have a streamline shape to reduce the water resistance ( friction force)

9. Alkarma Language School 1.Friction enables you to control the car speed. 2. Friction is necessary to light a match. 3. You can't walk without friction as it prevents your shoes from slipping on the ground. 4.Friction is important to change the car's direction.

10. Alkarma Language School friction force disadvantage The friction damages the internal parts of the machines. Because friction causes the rises in the temperature in the internal parts of machines parts.

11. Alkarma Language School Ways of decreasing the friction force 1. Using lubricants & oils in car engine 2. Ball bearings

12. Alkarma Language School Links http://www.youtube.com/watch?v=xs-KBAjktjE http://www.youtube.com/watch?v=qy-EJRDyt-A