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
electrical equipment, appliances and wiring in which the use of a nonconductive extinguishing agent prevents injury from electrical shock. don’t use water
class C fire
certain flammable metallic substances such as sodium, magnesium, and potassium
Class D fire
classifications of fire
- natural/accidental (Acts of God)
- Criminal (arson)
- suspicious (suspected to be arson although proof is lacking)
- unknown origin
what are all fires considered until proven otherwise?
natural/accidental
intentionally destroying or damaging a dwelling or other property by means of fire or explosives or other incendiary or infernal device
arson
fire or explosion which creates an imminent danger to life or great bodily harm, which risk was known or reasonably foreseeable to the actor
Aggravated arson
3 questions of arson investigation
where did the fire originate?
how was the fire started?
was the cause of the fire an accident or set intentionally?
profile of arson offender
white males, ~half under 18, broken/unstable homes, extensive criminal record, below average intelligence
4 methods of collection/preservation of arson evidence
- accelerant detection using k9s
- electronic detectors
- forensic light source/alternate light source
- field flame/burn test
what is a burn pattern
- fires burn up not out
- usually travel horizontally and follows the path of least resistance
- fires are drawn toward ventilation and follow fuel path
- V pattern - upwards then outwards
boundary between charred and uncharred material; puddle shaped ________ __ __________ on floors or rugs may indicate the use of a liquid accelerant
line of demarcation
mix of combustible substance and an oxidant that decomposes rapidly; usually used as propellants, including gun powders and pyrotechnics (smoke bombs, rockets, illumination devices)
low explosive
extreme rapidity which decomposition occurs; action is known as detonation; mining, demolition, military warheads, dynamite, cordite, ballistite, pipe bomb, homemade explosives, c4 explosives, molotov cocktail
High explosives
What is a document?
Any material substance that contains a representation of the thoughts of man by means of some mark or symbol
What is a questioned document
a document in its entirety or in part is subject to question as to authenticity and/or origin
Father of Questioned Document Examination and President of the American Society of Questioned Document Examiners
Albert S. Osborn
Provided crucial testimony in the Bruno Hauptmann trial
landmark case
As a result of his work and national attention, the questioned document field was included in many federal and state agencies
Lindbergh Baby Case
Qualifications for Forensic Document Examiners:
Training programs
Proficiency tests
Peer reviews
Professional organizations
Continuing education
Lectures
Court testimony
What is graphology?
the study of handwriting to reveal character traits of the writer
A person who performs critical examinations on disputed documents in order to establish genueness or expose forgery
Studies scientifically the entire document in order to recognize the source or other evidence that can determine authenticity
Forensic Document Examiner
what does a graphologist do? what can’t they determine?
profile a character or personality by drawing conclusions from certain types of characteristics in the handwriting sample; Do not compare handwriting to determine authenticity or origin; Lacks scientific proof
What cannot be determined with any degree of scientific certainty
Sex, writing hand, education, race, character, age, physical ability/disability
handwriting can be affected by illness, age, etc.
handwriting is just as unique as finger prints
what happens to an individuals writing as they mature?
writing becomes more of a subconscious effort
Habitual styles, shapes, and patterns are formed which distinguishes one’s writing from another
Most evident with capital letters and numerals
Unconscious handwriting of two different individuals is never identical
Mechanical, physical, mental factors
What is ACE?
3 step process of handwriting analysis
Analysis
Comparison
Evaluation
3 different signatures
Formal – used for important documents
Routine – regular correspondence
Informal – used for jotting quick notes
Significant similarities, no significant dissimilarities, or no associated with absent characters, dissimilarities or quantity of writing present
Identification
Range of variation in the questioned and the known contains substantial significant similarities, there are no significant dissimilarities and limitations are present
highly probably did write
Range of variation contains some significant similarities, no significant dissimilarities, limitations may be present
Probably did write
How are conclusions determined in QDE?
Most conclusions are based on qualified opinions
Opinion need not be based on absolute certainty
digital image taken through a microscope to show the magnified image of an item
1-50x magnification
Photomicrography
use of film or image sensor that is sensitive to infrared light but blocks out visible light
Infrared
The Dreyfus Case 1894
Alphonse Bertillon, the inventor of anthropometry, gave
testimony against a French army officer, Alfred Dreyfus.
* He was accused of treason through letters found,
attempting to sell French secrets to Germany.
* It wasn’t until years later, while Dreyfus was incarcerated,
that Bertillon’s mistaken opinion was challenged by well
known and established forensic document examiners in
England and the United States.
* With new evidence introduced, Dreyfus was finally
exonerated of the charges of treason.
1910 individual who noted differences in his stroke differences which he associated with personality traits
Milton Newman Bunker
Handwriting characteristics
slant, size, speed, connecting strokes, spacing, letter forms, i dot and t crossing
Fire does not consume the entire material
charring
Flaking or chipping of concrete
Rise in internal pressure due to evaporation
Internal cracking and thermal expansion
spalling
what is crazing
rapid cooling of glass
what is the point of origin
Established by area of deepest char
what is an incendiary fire
Fire set intentionally by human activity
examples of poor driver behavior
Distracted driving, speeding, tailgating, cutting others off, not using turn signals, merging improperly, not checking blind spots, driving under the influence, accelerating through yellow lights, not driving according to conditions
