[!def]
Friction is the force that opposes motion between any surfaces that are in contact

Static (Starting) Friction

[!def]
Static friction is the force keeping a motionless object from being pushed or pulled across a surface.

Includes rolling friction

Dynamic (Kinetic) friction

[!def]
Kinetic friction acts to resist the motion of an object sliding across a surface

Fluid

Air resistance
Drag

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  1. The distance travelled after it starts breaking, before it stops.
  2. FALSE
  3. 0.2s-0.4s tiredness,
  4. it might increase the breaking distance, because the pressure will be smaller, also the friction. So deceleration is smaller.
  5. rain will let the surface of road become slipper, so friction between the tire and the road will be smaller. Deceleration will be smaller.
  6. ruler drop experiment \frac{1}{2}gt^2 = s t = \sqrt{ \frac{2s}{g} }
  7. an increase of reaction time will cause an increase in stop distance, increasing the possibility to crash.