Friction

Friction is a force, affects motion. Friction acts on materials in contact with another, or acts in different direction in opposite motion.

• Nature of the materials.
• How hard the surfaces are pressed together

..such as Rubber vs. Concrete, and not Steel vs. Steel (Rubber vs. Concrete > Steel vs. Steel)

Friction between the surfaces in contact and which are relatively at rest.

• Opposes movement of stationary object
• Moving furniture
• Hardest part getting moving

• Acts on objects in motion
• Once object begins moving, less force to keep in motion
• Sliding, Rolling, Fluid

• Two objects slide past one another
• Basketball shoes prevent slipping

• Objects such as wheel or ball rolls across surface
• Easier to overcome than sliding friction
• Rolling friction is always less than static friction, as the time period for contact of irregularities between the bodies is less in rolling friction compared to static friction.

• Solid objects move through fluids
• Cyclists use aerodynamic and spandex to reduce friction
• Vehicles such as aeroplanes and cars have a special shape known as streamlined shape to reduce windshear or drag.

• Friction acting on something moving through air
• Don't notice unless at high speed.