How Far? Measuring Friction Using Different Materials
To learn how friction affects motion, students explore how different textures provide varying amounts of friction to objects moving across them. They build a tool to measure the amount of friction between a note card and various surfaces by measuring the distance that a rubber band stretches. They experiment with a range of materials to determine which provides the least/most friction.
Friction is generated as the baseball player slides, slowing him down.Copyright Wikimedia Commons http://commons.wikimedia.org/wiki/File:Sliding_Into_Home.jpg
Engineers consider friction when determining materials for tires, runways, shoe soles, motors or hip replacements. Chemical engineers consider friction when they design compounds for glues, bubble gum or brake pads. Some bicycle tires use a mix of materials because friction is different on the flat of the tire vs. the curve of the tire. Engineers also consider the consequences of frictional forces. For example, friction on the thin brake disks of performance cars can raise the temperature of the disk high enough to warp it, so engineers design the brake disk with holes so it cools down faster.
After this activity, students should be able to:
- Understand that friction is stronger between some surfaces than others.
- Be able to suggest methods of affecting the friction between surfaces.
- Understand why friction is an important consideration in many areas of engineering design.