Test 3 Flashcards
4 factors that contribute to the overwhelming number of crashes
- Mechanical failure
- Roadway design
- Poor road maintenance
- Driver behavior
Good quality tires for handling and agility, can be noisy and uncomfortable, higher priced
low profile tire
low cost, comfortable ride, good gas milage, bad stability and agility
high profile tire
everything but the tread and belt system
tire casing
the footprint of the tire; the point where the face of the tire meets the surface
contact patch
best for unpaved roads, sharp curves, and irregular intersections; 2 fixed base points all measurements made from here should be widely spaced for less error
triangulation method
best for roads with well defined edges and when measurements are within 25 ft of edge; road edge is first coordinate (zero/reference point); distance to object (measured at a right angle to first coordinate is second coordinate))
coordinate method
determining vehicle speed
- skid distance
- drag factor
- road surface
- braking efficiency
a tire mark on the road surface produced by a tire that is locked, not rotating
skid mark
the sum of the visible skid marks divided by the number of marks present
skid distance (D)
the interface between the tire and road surface
drag factor
visible evidence at accident scenes
- yaw marks
- acceleration scuffs
- deceleration marks
- imprint marks
left by a tire that is still rolling by simultaneously sliding laterally
yaw marks
components of disc brake
- wheel bearing
- caliper assembly
- disc pads
- wheel studs
- disc/rotor
5 top reasons why tires fail
- damaged
- deterioration
- overinflation
- underinflation
- age
top 4 reasons brakes fail
- grease/oil on breaks
- overheated
- worn down brake pads
- leaking brake fluid
if all 4 wheels brake evenly and leave 4 distinct skid marks, what is the braking efficiency?
100% or 1.0
Variables to calculate speed
S = √ 30 x D x f x n
S = minimum speed (mph)
30 = constant for equation
D = skid distance in decimal feet and inches
f = drag factor for the road surface
n = braking efficiency as a percent
What is the fire triangle?
oxygen, heat, fuel
examples of fuels
liquids - gasoline, acetone
solids - plastic, wood dust, fibers
gases - acetylene, propane, hydrogen
examples of oxidizers
gases - oxygen, fluorine, chlorine
liquids - hydrogen, peroxide, nitric acid
solids - metal peroxides, ammonium nitrate
examples of ignition sources
sparks, flames, static electricity, heat
what is a fire?
a rapid, self sustaining oxidation process usually accompanied by the evolution of heat and light in varying intensities
the rapid increase in volume and release of energy in an extreme manner; the result, not the cause, of a rapid expansion of gases
explosion
ordinary solid combustibles such as paper, wood, cloth, and some plastics
class A fire
flammable liquids such as alcohol, ether, oil, gasoline and grease, which are best extinguished by smothering
class B fire