Friction
What is friction?
editFriction is a force, affects motion. Friction acts on materials in contact with another, or acts in different direction in opposite motion.
What does the force of friction depend on?
edit- 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)
Static Friction :
editFriction between the surfaces in contact and which are relatively at rest.
- Opposes movement of stationary object
- Moving furniture
- Hardest part getting moving
Kinetic Friction
edit- Acts on objects in motion
- Once object begins moving, less force to keep in motion
- Sliding, Rolling, Fluid
Sliding Friction
edit![](http://upload.wikimedia.org/wikipedia/commons/thumb/9/95/Ray_Lee_basketball_player_class_of_2012_Romulus_High_school.jpg/220px-Ray_Lee_basketball_player_class_of_2012_Romulus_High_school.jpg)
- Two objects slide past one another
- Basketball shoes prevent slipping
Rolling Friction
edit- 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.
Fluid Friction
edit![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/63/Boy_with_helmet_on_training_wheels.jpg/220px-Boy_with_helmet_on_training_wheels.jpg)
- 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.
Air Resistance
edit- Friction acting on something moving through air
- Don't notice unless at high speed.
quiz
edit