1. Friction
Dr. Lee Science Class

2. Today's L.O.
To take part in a range of activities to explore the world around them, and ask questions and suggest answers (E)

3. What is Friction?
Friction is a force between two surfaces that are sliding, or trying to slide across one another, for example when you try to push a toy car along the floor.
Friction always works in the direction opposite from the direction the object is moving, or trying to move. It always slows a moving object down.
Moving
Friction

4. What is Friction?
The amount of friction depends on the materials from which the two surfaces are made. The rougher the surface, the more friction is produced. For example, you would have to push a book harder to get it moving on a carpet than you would on a wooden floor. This is because there is more friction between the carpet and the book than there is between the wood and the book.

5. What is Friction?
Friction also produces heat. For example, if you rub your hands together quickly, they get warmer.

6. Useful Friction and Reducing Friction.
Friction can be a useful force because it prevents our shoes slipping on the pavement when we walk and stops car tyres skidding on the road.

7. Useful Friction and Reducing Friction.
Ice causes very little friction, which is why it is easy to slip over on an icy day. But this is a good thing for ice skating and sledging.

8. Useful Friction and Reducing Friction.
Sometimes we want to reduce friction. For example, moving parts inside a car engine are lubricated with oil, to reduce friction between them. The oil holds the surfaces apart, and can flow between them. The reduced friction means there is less wear on the metal, and less heat produced.

9. Air Resistance
Air resistance is a type of friction between air and another material. When an aeroplane flies through the air, for example, air particles hit the aeroplane, making it more difficult for the aeroplane to move through the air.

10. Air Resistance
Some shapes, known as streamlined shapes, cause less air resistance than others. Aeroplanes and cars are streamlined, so that they move through the air as easily as possible.

11. Quiz Time!!
Quiz

12. Friction Quiz
1. A puck slides along an icy surface. What makes it slow down?
It runs out of push
It rubs against the ice
 It runs out of electricity

13. Friction Quiz
2. A boy sits halfway down a grassy slope. What force stops him sliding down?
A. Weight
Gravity
Friction

14. Friction Quiz
3. On which surface will a toy sledge travel the furthest?
A. Carpet
B. Polished wood
C.  Ice

15. Friction Quiz
4. On which surface will a toy sledge travel the least distance?
A.  Carpet
B. Polished wood
C. Ice

16. Friction Quiz 5. Rougher surfaces have ... A. greater friction
B.  less friction
C.  the same level of friction

17. Friction Quiz
6. Which of the following is an example of trying to increase friction?
A. Squirting oil into door hinges
Spreading grit on icy roads
 Waxing the underneath of skis

18. Friction Quiz 7. Which of the following statements is true?
Friction is a force that only occurs between solids
 Friction is a force that only occurs on rough surfaces
 Friction is a force that only occurs when surfaces touch each other

19. Friction Quiz 8. Which of the following statements is false?
Friction can only slow things down
Friction is never useful
Friction can stop things from moving

20. Friction Quiz
9. Air resistance and water resistance are both types of friction. Is this true or false?
True
False
Neither true nor false

21. Friction Quiz
10. If you poured oil onto a wooden surface, the friction would ...
be reduced
be increased
remain the same