Stress Marks
For a concentric fracture,
the perpendicular end always faces the surface on which the force originated
. These facts enable the examiner to readily determine the side on which a window was broken. Unfortunately, tempered glass does not produce reliable cracking patterns for study.
What can be analyzed when a projectile breaks glass?
Radial fractures are similar to the spokes of a wheel. … Once the technician finds radial fracture and determines which side of the glass faced where, they must look at the broken edge of the glass. When a projectile strikes glass, it creates ridges called
conchoidal fractures
along the edge that are visible in profile.
What do stress marks tell you about a glass fracture?
Stress Marks
For a concentric fracture,
the perpendicular end always faces the surface on which the force originated
. These facts enable the examiner to readily determine the side on which a window was broken. Unfortunately, tempered glass does not produce reliable cracking patterns for study.
How can you tell if spontaneous glass is broken?
Breakages due to
Nickel Sulfide
Looking at the broken glass will give an initial impression of glass being hit by a sharp object and the point of origin of breakage will be obvious. On closer examination, at the origin, there will be at least two fragments in the shape of wings of the butterfly.
What are glass fracture patterns?
When a projectile i.e. a bullet or rock hits the glass, it will form two distinct types of fractures:
Radial and Concentric
. … The radial cracks begin on the opposite side of the force at the point where the projectile hits the glass and radiate out from the origin of the impact.
What is the 3R rule for glass fractures?
The 3R rule states that
Radial cracks form a Right angle on the Reverse side of the force
. This rule enables an examiner to determine readily the side on which a window or pane of glass was broken.
What are the two most often used methods of glass analysis?
The
flotation and immersion methods
are best used to determine a glass fragment’s density and refractive index, respectively.
What is normal line in glass?
normal line.
a line drawn perpendicular to the interface surface of two different media
.
How do you test glass evidence?
Forensic glass samples can be analyzed by
comparing the refractive index of the sample
to that of the possible source. Examination of samples under a regular microscope or a scanning electron microscope can give detailed information about the sample’s physical and chemical characteristics.
What are radial lines in a glass fracture pattern?
Radial cracks are
fractures extending outward from the point of impact
. Ream is an imperfection; nonhomogeneous layers of flat glass. Wallner lines (ridges) are rib-shaped marks with a wave-like pattern.
What is the spiritual meaning of breaking glass?
Breaking a Glass
Paradoxically, the circumstance of breaking a glass accidentally is
good luck
. It represents the fact that evil is leaving and good luck is on the way. With the noise and chaos of the breaking glass, evil spirits are said to get flustered and run away.
How much force does it take to break tempered glass?
Depending on the manufacturer, the force required to break tempered glass ranges from
20,000 to 24,000 PSI
(or pounds per square inch). This sounds like a lot, and it certainly is: there’s a reason tempered safety glass is used on modern car windows. Unique shattering.
Is there anyway to cut tempered glass?
The only possible way to cut & customize tempered glass is
with the use of special laser cutters
, and this cannot be done at home. So, homeowners must seek professional help if they really need to cut & customize the tempered glass without making it lose its strength & durability.
What 2 characteristics do high velocity bullets leave in glass?
When it penetrate glass, a high velocity projectile such as bullet often leaves
a round, crater shaped hole that is surrounded by a nearly symmetrical pattern of radial and concentric cracks
.
What type of evidence is glass class or individual?
However, glass is usually
class evidence
therefore the value of evidence will depend on the discrimination powers of techniques used for its comparison. It is class evidence most of the time because without two fitting glass fragments, the glass can be identified but not linked to a specific object.
What is the main ingredient in ordinary glass?
| Question Answer | what is the main ingredient in ordinary glass sand | Tempered glass is used in the side and rear windows of autos manufactured in the United States | Flotation is a method used by scientists to determine the ____ of a particle of glass density |
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