Concentric cracks are fractures forming in an approximately circular pattern around the point of impact. ... Radial cracks are fractures extending outward from the point of impact . Ream is an imperfection; nonhomogeneous layers of flat glass.
What are radial and concentric fractures used to determine?
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 . Concentric cracks are fractures forming in an approximately circular pattern around the point of impact.
What is the difference between radial and concentric fractures which form first?
A radial fracture is the first fracture that forms on the surface opposite that of the penetrating force, concentric fractures are formed by the continued motion of the force which places tension on the front of the surface and encircle the hole.
Why do radial and concentric fractures form?
As the first fractures form on the surface opposite that of the penetrating force, and these fractures develop into radial lines. The continued motion of the force places tension on the front surface of the glass , resulting in the’ formation of concentric cracks.
What are the 2 types of glass fractures cracks?
When a projectile i.e. a bullet or rock hits the glass, it will form two distinct types of fractures: Radial and Concentric .
What is the 3r rule?
The three R’s stands for: Reduce, Reuse and Recycle . This rule is part of the waste hierarchy which is a process used to protect the environment and conserve resources through a priority approach. The aim is to get the most practical benefits from products and to generate the minimum amount of waste.
Is hair biological or physical evidence?
Physical versus biological evidence
Forensic evidence can be divided into two basic categories: physical and biological. ... Biological evidence , on the other hand, includes organic things like blood, saliva, urine, semen, hair, and botanical materials, such as wood, plants, pollens and yes, Clarice, moth cocoons.
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 are the two steps in comparison?
what are two steps in comparison? A comparison analysis subjects a suspect specimen and a standard/reference specimen to the same tests and examinations to determine whether they have a common origin.
What determines the value of soil as evidence?
The variation in soils from place to place makes soil valuable evidence to prove linkage between a suspect and a crime scene. Soil is a complex mixture with a variety of mineralogical, chemical, biological, and physical properties. ... The systematic observation of multiple soil colors is especially useful for screening.
How is glass analysis used in forensic science?
A forensic glass analysis is typically a comparison of two or more glass fragments in an attempt to determine if they originated from different sources . Less frequently, it is a question of determination of end use, or glass provenance. ... The aim of a comparative glass analysis is to exclude possible sources.
What tests are conducted on glass as evidence?
Glass: Glass can yield valuable information through fracture marks, lines and patterns. Testing for unique characteristics such as color, optical properties and density can determine the type of glass, for example a window pane, vase or glass bottle.
What are two morphological characteristics criminalist?
What two morphological characteristics does a criminalist first compare when examining fibers with a microscope? What other features may be important in such a comparison? Color and diameter . Other features would include lengthwise striations and the cross sectional shape of a fiber.
What is normal line in glass?
normal line. a line drawn perpendicular to the interface surface of two different media .
What are the 3R rules for glass fractures?
This is the forensic scientists’ [3R] rule— radial cracks make right angles to the rear . In a concentric crack, it’s the opposite—the chonchoidal fractures DO make a right angle to the side the force came from. This can be vitally important in determining if something was a shoot-out or a shoot-in.
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 .
