1. Friction
“Friction is a Force that always pushes against an object when it touches another object”
“When 2 things are in contact with each other, there will be friction acting between them”

2. What factors affect friction?
Types of surfaces
How hard the surface is
How soft the surface is
Texture of the surface
How much Force is applied
i.e. Gravity

3. Friction Creates Heat
High friction (lots of friction) – will slow something down and create a lot of heat
Low friction (not much friction) – will keep things moving and reduce the creation of heat

4. High friction or Low friction?
Skis on the snow
Car tire
Brakes on a bike Water on a slide
Pencil and eraser

5. Types of Surfaces Smoother the surface- smaller the friction
Ice
Glass
Tile
The rougher the surface- greater the friction
Carpet
Roads
Sandpaper

6. What happens when we change a surface?
How does adding rubber to the bottom of an object change the friction?
What happens when the gym floor is dusty?
How are other ways a surface changes the friction?

7. Types of Friction Static Sliding Objects that aren’t moving
Think about trying to push something that just won’t move
Example: Push the wall.
Sliding
Two solid surfaces slide over each other
Direction of motion is OPPOSITE that of friction
Example: Push your chair.

8. Types… cont’d Rolling Drag When an object rolls across a surface
Easier to overcome than sliding friction
Example: Push Mr. Bryan’s Chair.
Drag
When a solid object moves through the Air
Easier to overcome than rolling
Example: Throw a Paper Airplane.

9. Paper Airplane Competition
Aim:
The winning team is the one who gets their plane to stay in the air the longest and is the fastest.
Materials:
1 sheet of blank paper
1 paperclip
Scotch tape
Instructions:
Use only the materials indicated in the above list; you don’t have to use them all.
The plane may be constructed using all or part of the sheet of paper.
Label each plane with your team name.
Each group is allowed three throws; record the best throw only.
Begin timing with the throw of the plane and end when the plane hits the floor.
Settle a tie with a throw-off.