|
WHAT WILL YOU DO?:
Is it easier to push a heavy box across a thick carpet or a slick patch of ice? It is easy to push it over the ice. Why? There is less friction between the ice and the box than there is between the thick carpet and the box. Friction can make objects hard to push. Two demonstrations illustrating these principles are presented.
STEPS TO FOLLOW:
 |
Demonstration 1:
Drop a few marbles, a short distance above the smooth surface. What
did you observe? Is there much friction between the marbles and the
smooth surface?
|
 |
What do you think will happen when the marbles are dropped on the piece of
rough sandpaper? Try to drop the marbles onto the sandpaper from the same height as in Step 1. What happened?
|
 |
Demonstration 2:
Before the lecture/class period, pour the water on the cookie sheet and let it f
reeze. Prepare the other 3 surfaces for the demonstration.
|
| |
MATERIALS:
3 Marbles
A Smooth Surface (Example, A Tile Floor Or A Large Smooth Tabletop)
Piece Of Very Rough Sandpaper (6 Inches X 6 Inches Or Larger)
3 Coins
A Wooden Surface (Cutting Board or Desk Top)
A Carpeted Surface Or A Piece Of Carpeting
A Cookie Sheet
Water Piece Of Plywood Or Very Sturdy Cardboard
Access To A Freezer
 |
What do you think will happen when you flick a coin across the following surfaces: wood, carpet, ice, sandpaper? Which will have the most friction? Which will have the least friction? Flick the coins across each surface. Try to use the same amount of force each time. What happens if you use more force to flick the coin across the surfaces?
|
|
