A Pane in the Glass
Crack Me Up
Bullet Points
Crystal Clear
Shattered Dreams
100
This is the most common and least expensive type of glass and is commonly used for windows and containers.
What is soda-lime-silica glass?
100
These cracks extend outward from the point of impact.
What are radial cracks?
100
Which generally produces a larger central hole in glass: a higher-velocity projectile or a lower-velocity projectile?
What is a lower-velocity projectile?
100
This property is calculated by comparing the mass of a substance to its volume.
What is density?
100
Small glass shards should generally be packaged in this type of material rather than being left loose.
What is a paper bindle?
200
Glass product that is stronger than ordinary glass & will break into many small pieces rather than large dangerous shards.
What is tempered glass?
200
These cracks form circular patterns around the point of impact.
What are concentric cracks?
200
This side generally has the smaller opening when a projectile passes completely through a piece of glass.
What is the entrance side?
200
This property describes how light changes direction as it passes from one material into another.
What is refractive index?
200
This tool can be used to carefully collect small glass shards.
What are tweezers/forceps?
300
This type of glass is designed to resist sudden changes in temperature.
What is borosilicate glass?
300
These fractures have a curved, shell-like appearance.
What are conchoidal fractures?
300
Determine the sequence of impacts
What is D, B, C, A?
300
Investigators can learn this when a glass shard sinks when placed into a particular liquid.
The glass is more dense than the liquid.
300
A crack stops when it reaches another existing crack. What can investigators determine from this observation?
What is the sequence of impacts? The crack that continues existed before the crack that stopped.
400
This type of glass has an increased shine.
What is lead glass/crystal?
400
A window has curved, relatively smooth fracture edges & investigators cannot identify a clear point of impact. This is the most likely cause.
What is heat stress?
400
Investigators can determine this when they find a smaller hole on one side of a window and a larger hole on the opposite side.
What is the direction of projectile travel?
400
A forensic scientist places a glass shard into an immersion liquid and gradually changes the temperature. Eventually, the glass becomes difficult to see and the bright Becke line disappears. What has the scientist reached, and what does it tell them?
The match point has been reached. The refractive index of the liquid matches the refractive index of the glass.
400
An investigator finds several glass shards at a crime scene. They pick them up with gloved hands and put them into a loose plastic bag. Identify two problems with this collection method.
The shards should be collected with appropriate tools such as tweezers; small shards should be placed in appropriate paper packaging; large shards should be wrapped in paper & put in a sturdy container to protect it from breaking again.
500
A vehicle window is broken & much of the glass remains attached to the frame. Identify the type of glass & explain why it doesn't leave the frame.
What is laminated glass?
It contains a plastic layer between sheets of glass that helps hold the pieces together.
500
The force came from this direction.
What is from below?
500
A projectile passes through a window. Investigators find radial cracks that form at right angles on the inside surface of the glass. Investigators can determine this.
The direction of the force. The force came from the outside, toward the inside.
500
Investigators have a glass shard from a crime scene and a piece of glass from a suspect's vehicle. Name three properties they could compare to determine whether the samples may have originated from the same source.
density, refractive index, thickness, and color
500
FINAL JEOPARDY - Investigators arrive at a burglary scene and find a broken window. They determine:
- The radial cracks form right angles on the inside surface.
- Glass shards are found inside the building.
- The same type glass is recovered from a suspect's vehicle.
Using the evidence above, determine:
- The direction of force
- If the suspect is guilty
- Force came from outside toward the inside based on the 3R Rule.
- Suspect guilt CANNOT be determined.