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”

What factors affect friction?

Types of surfacesHow hard the surface isHow soft the surface isTexture of the surfaceHow much Force is applied i.e. Gravity

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

High friction or Low friction?

Skis on the snow

Car tire

Brakes on a bike Water on a slide

Pencil and eraser

Types of Surfaces

Smoother the surface- smaller the friction Ice Glass Tile

The rougher the surface- greater the friction Carpet Roads Sandpaper

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?

Types of Friction

Static 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.

Types… cont’d

Rolling 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.

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.