What is the difference between radial and concentric fractures explain?
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.
What are concentric cracks What is their role in determining the direction of impact of an object on glass?
If a pane is firmly held on all sides, concentric cracks can form around the point of impact. By observing the Wallner lines (ridges) on the radial cracks, the direction of breaking force can often be determined.
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. There is another terminology that is known as cone fracture, observed to be caused by a penetration of the high velocity projectile such as a bullet.
What type of glass fracture forms a circle?
Concentric fracture- A crack in a glass that forms a rough circle around the point of impact.
What tests are conducted on glass as 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 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 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.
Which glass fracture comes first?
Radial fractures
What is a thermal crack in glass?
Thermal fracturing in glass occurs when a sufficient temperature differential is created within glass. As a warmed area expands or a cooled area contracts, stress forces develop, potentially leading to fracture.
Why is glass class evidence?
Very small glass fragments would not fit together well, some fragments would probably not be found at all. This would make it more difficult to put the pieces together and match to the rest of the bottle; so this is class evidence.
Is glass direct or circumstantial evidence?
also known as direct evidence or prima facie evidence. Physical evidence is any object or material that is relevant in a crime; also known as indirect evidence. Examples are hair, fiber, fingerprints, documents, blood, soil, drugs, toolmarks, impressions, glass.