FLETC WRITTEN EXAM 4 QUESTIONS
AND ANSWERS 100% PASS 2026/2027
Three Types of Explosions - ANS Mechanical
Chemical
Nuclear
High Explosive - ANS Explosive which normally requires a blasting cap for initiation and once
initiated produces a supersonic detonation with a shattering or brisant effect
Detonate without confinement, doesn't need container
Low Explosive - ANS Explosive, which when unconfined, responds to initiation by deflagration
or burning and produces a pushing effect
Transitions from deflagration to detonation when confined
Incendiary Explosive - ANS Explosive designed to start fires or destroy sensitive equipment
Detonation - ANS Supersonic combustion that propagates through shock compression
generating exothermic heat and an accompanying blast wave
2026/2027 ALLRIGHTS RESERVED
1
,Deflagration - ANS A subsonic combustion that propagates through thermal conductivity
Effects of an Explosion - ANS Thermal
Blast Pressure
Fragmentation
Thermal Effect - ANS Usually seen as a bright flash or fireball at the moment of detonation
May cause localized ignition of highly combustible materials
Generally least damaging of the three effects
Blast Pressure Effect - ANS Very hot gasses (between 3,000 and 7,000 degrees Fahrenheit)
expand out from the point of detonation at supersonic velocities (up to 20,000 mph)
The further the pressure wave travels, the less power it has
Most powerful and destructive/deadly of the effects
When taking place in a confined area, it can amplify the original blast wave
Two Phases of Blast Pressure - ANS Positive Phase
Negative Phase
Positive Phase of Blast Pressure - ANS Pressure wave moving outward from the point of
detonation
Negative Phase of Blast Pressure - ANS Partial vacuum is created near the epicenter due to
the outward movement of air and the consumption of oxygen from the combustion process
2026/2027 ALLRIGHTS RESERVED
2
,4 Types of Injuries Sustained During a Blast - ANS Primary Blast Injury
Secondary Blast Injury
Tertiary Blast Injury
Quaternary Injury
Primary Blast Injury - ANS Caused by direct effects of blast
Secondary Blast Injury - ANS Caused by propelled fragmentation (most deadly)
Tertiary Blast Injury - ANS Occurs when a casualty's body is propelled by the blast against the
ground or stationary objects
Quaternary Injury - ANS Any other injuries (burns and crush injuries)
Three Mechanisms of Primary Blast Injury - ANS Implosion
Spalling
Inertial Effects
Implosion - ANS Occurs when blast impacts the human body by compressing air-filled cavities
in the body and causes tissue damage as compressed air stretches, tears, and ruptures internal
organs and tissues
Spalling - ANS Describes tissue injury caused when blast wave rapidly changes velocity as it
moves through tissues of different densities
Blast Lung - ANS Severe form of pulmonary contusion, crushed lung tissue fills with blood
and cannot exhange oxygen
2026/2027 ALLRIGHTS RESERVED
3
, Inertial Effects - ANS Injury occurring when connected tissues of different densities move at
different velocities
Progressive Collapse - ANS Refers to the spread of an initial local failure from element to
element, eventually resulting in a disproportionate extent of collapse relative to the area of
initial blast damage
Two Types of Progressive Collapse - ANS Pancaking
Cascading
Pancaking - ANS Occurs when an explosion destroys a structural member or members,
causing floor directly above destroyed members to collapse and the floor above that to collapse
and so on
Cascading - ANS Collapsing of a series of bays from the destruction of one or few bays
Fragmentation Effect - ANS When an encased explosive such as a pipe bomb detonates, the
rapidly expanding gases produced by the explosion enlarge the casing to about one and one-
half times its original diameter before it ruptures
When it ruptures, the casing breaks into fragments that are propelled away from the center of
detonation
Primary Fragmentation - ANS Has intimate contact with explosive material or is produced by
the explosive container/device
Yields incriminating forensic evidence
Secondary Fragmentation - ANS Objects propelled from around detonation point, and
fractured pieces of the intended target that become lethal missiles
2026/2027 ALLRIGHTS RESERVED
4
AND ANSWERS 100% PASS 2026/2027
Three Types of Explosions - ANS Mechanical
Chemical
Nuclear
High Explosive - ANS Explosive which normally requires a blasting cap for initiation and once
initiated produces a supersonic detonation with a shattering or brisant effect
Detonate without confinement, doesn't need container
Low Explosive - ANS Explosive, which when unconfined, responds to initiation by deflagration
or burning and produces a pushing effect
Transitions from deflagration to detonation when confined
Incendiary Explosive - ANS Explosive designed to start fires or destroy sensitive equipment
Detonation - ANS Supersonic combustion that propagates through shock compression
generating exothermic heat and an accompanying blast wave
2026/2027 ALLRIGHTS RESERVED
1
,Deflagration - ANS A subsonic combustion that propagates through thermal conductivity
Effects of an Explosion - ANS Thermal
Blast Pressure
Fragmentation
Thermal Effect - ANS Usually seen as a bright flash or fireball at the moment of detonation
May cause localized ignition of highly combustible materials
Generally least damaging of the three effects
Blast Pressure Effect - ANS Very hot gasses (between 3,000 and 7,000 degrees Fahrenheit)
expand out from the point of detonation at supersonic velocities (up to 20,000 mph)
The further the pressure wave travels, the less power it has
Most powerful and destructive/deadly of the effects
When taking place in a confined area, it can amplify the original blast wave
Two Phases of Blast Pressure - ANS Positive Phase
Negative Phase
Positive Phase of Blast Pressure - ANS Pressure wave moving outward from the point of
detonation
Negative Phase of Blast Pressure - ANS Partial vacuum is created near the epicenter due to
the outward movement of air and the consumption of oxygen from the combustion process
2026/2027 ALLRIGHTS RESERVED
2
,4 Types of Injuries Sustained During a Blast - ANS Primary Blast Injury
Secondary Blast Injury
Tertiary Blast Injury
Quaternary Injury
Primary Blast Injury - ANS Caused by direct effects of blast
Secondary Blast Injury - ANS Caused by propelled fragmentation (most deadly)
Tertiary Blast Injury - ANS Occurs when a casualty's body is propelled by the blast against the
ground or stationary objects
Quaternary Injury - ANS Any other injuries (burns and crush injuries)
Three Mechanisms of Primary Blast Injury - ANS Implosion
Spalling
Inertial Effects
Implosion - ANS Occurs when blast impacts the human body by compressing air-filled cavities
in the body and causes tissue damage as compressed air stretches, tears, and ruptures internal
organs and tissues
Spalling - ANS Describes tissue injury caused when blast wave rapidly changes velocity as it
moves through tissues of different densities
Blast Lung - ANS Severe form of pulmonary contusion, crushed lung tissue fills with blood
and cannot exhange oxygen
2026/2027 ALLRIGHTS RESERVED
3
, Inertial Effects - ANS Injury occurring when connected tissues of different densities move at
different velocities
Progressive Collapse - ANS Refers to the spread of an initial local failure from element to
element, eventually resulting in a disproportionate extent of collapse relative to the area of
initial blast damage
Two Types of Progressive Collapse - ANS Pancaking
Cascading
Pancaking - ANS Occurs when an explosion destroys a structural member or members,
causing floor directly above destroyed members to collapse and the floor above that to collapse
and so on
Cascading - ANS Collapsing of a series of bays from the destruction of one or few bays
Fragmentation Effect - ANS When an encased explosive such as a pipe bomb detonates, the
rapidly expanding gases produced by the explosion enlarge the casing to about one and one-
half times its original diameter before it ruptures
When it ruptures, the casing breaks into fragments that are propelled away from the center of
detonation
Primary Fragmentation - ANS Has intimate contact with explosive material or is produced by
the explosive container/device
Yields incriminating forensic evidence
Secondary Fragmentation - ANS Objects propelled from around detonation point, and
fractured pieces of the intended target that become lethal missiles
2026/2027 ALLRIGHTS RESERVED
4
