FLETC Written Exam 4 With Verified Answers Latest Updated 2024/2025 Graded A+.

FLETC Written Exam 4 With Verified Answers Latest Updated 2024/2025 Graded A+. High Explosive - ANSWER 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 - ANSWER 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 - ANSWER Explosive designed to start fires or destroy sensitive equipment Detonation - ANSWER Supersonic combustion that propagates through shock compression generating exothermic heat and an accompanying blast wave Deflagration - ANSWER A subsonic combustion that propagates through thermal conductivity Effects of an Explosion - ANSWER Thermal Blast Pressure Fragmentation Thermal Effect - ANSWER 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 - ANSWER 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 FLETC Written Exam 4 With Verified Answers Latest Updated 2024/2025 / Graded A+ Two Phases of Blast Pressure - ANSWER Positive Phase Negative Phase Positive Phase of Blast Pressure - ANSWER Pressure wave moving outward from the point of detonation Negative Phase of Blast Pressure - ANSWER Partial vacuum is created near the epicenter due to the outward movement of air and the consumption of oxygen from the combustion process 4 Types of Injuries Sustained During a Blast - ANSWER Primary Blast Injury Secondary Blast Injury Tertiary Blast Injury Quaternary Injury Primary Blast Injury - ANSWER Caused by direct effects of blast Secondary Blast Injury - ANSWER Caused by propelled fragmentation (most deadly) Tertiary Blast Injury - ANSWER Occurs when a casualty's body is propelled by the blast against the ground or stationary objects Quaternary Injury - ANSWER Any other injuries (burns and crush injuries) Three Mechanisms of Primary Blast Injury - ANSWER Implosion Spalling Inertial Effects Implosion - ANSWER 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 - ANSWER Describes tissue injury caused when blast wave rapidly changes velocity as it moves through tissues of different densities Blast Lung - ANSWER Severe form of pulmonary contusion, crushed lung tissue fills with blood and cannot exhange oxygen Inertial Effects - ANSWER Injury occurring when connected tissues of different densities move at different velocities Progressive Collapse - ANSWER 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 - ANSWER Pancaking Cascading Pancaking - ANSWER 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 - ANSWER Collapsing of a series of bays from the destruction of one or few bays Fragmentation Effect - ANSWER 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 - ANSWER Has intimate contact with explosive material or is produced by the explosive container/device Yields incriminating forensic evidence Secondary Fragmentation - ANSWER Objects propelled from around detonation point, and fractured pieces of the intended target that become lethal missiles Firebrand - ANSWER Projected hot fragmentation, burning energetic material, or burning debris whose thermal energy is transferred to the surroundings IED - ANSWER A device placed or fabricated in a manner incorporating destructive, lethal, noxious, pyrotechnic, or incendiary chemicals designed to kill, destroy, incapacitate, harass, or distract It could incorporate military, commercial, or homemade explosives, or military ordnance but is normally devised from nonmilitary components Four Components of IEDs - ANSWER Power Source Initiator Explosive Switch (PIES) Power Source - ANSWER Electric Initiator: battery Mechanical Action: spring under pressure Ignition: heat source such as flame or time fuse Initiator - ANSWER Blasting caps are used to initiate high explosives Electric caps are distinguished by two electric lead wires and needs only 1 .5 amps to function Non-electric has a hollow recessed cavity end to accept insertion for fuse or detonation cord. Explosives - ANSWER Black Powder Pyrodex Smokeless Powder Pipe Bombs Maglite flashlights Black Powder - ANSWER Most sensitive of all bulk explosives Pyrodex - ANSWER Synthetic black powder Less sensitive and less corrosive than black powder Smokeless Powder - ANSWER Contains nitroglycerin and has more potential energy than black powder Pipe Bomb - ANSWER Made by filling a metal or PVC pipe with a low explosive Three Explosive Classes of High Explosives - ANSWER Primary Secondary Tertiary or Blasting Agents Primary Explosives - ANSWER Extremely susceptible to heat, mechanical shock and friction; will respond by detonating Secondary Explosives - ANSWER aka base explosives Relatively insensitive to heat, shock, and friction to prevent unintended explosions May burn when exposed to heat or flame Tertiary Explosives - ANSWER aka Blasting Agents Insensitive to shock and they cannot be reliably detonated with practical quantities of primary explosive; require an intermediate explosive booster of secondary explosive Military High Explosives - ANSWER Composition C4 Semtex PE-4A TNT PETN Commercial High Explosives - ANSWER Dynamite Tovex Binary Explosive Binary Explosive - ANSWER An explosive consisting of two components, ammonium nitrate and nitromethane, neither of which is dangerous by itself, but become explosive when combined Homemade Explosives - ANSWER Potassium Chlorate and Sugar Mixture TATP HMTD Switches - ANSWER Used to arm/initiate device Arming Switch - ANSWER Safety device for the bomber; works by electrically isolating the triggering switch from the power source 3 Primary IED Methods of Initiation - ANSWER Timed Victim-Operated Command Vehicle-Borne IED - ANSWER Vehicle modified to conceal and deliver a large IED to a target for the purpose of inflicting mass casualties and catastrophic property damage Bombings where vehicle involved forms and integral part of the IED 2 Primary Differences Between IED and VBIED - ANSWER Size of device Vehicle 3 Primary VBIED Methods of Initiation - ANSWER Timed Command Suicide IED Exterior Building Search - ANSWER Outside to Inside Bottom to Top Public to Private IED Interior Building Search - ANSWER Start from bottom, move up in levels Start with public areas IED Individual Room Search - ANSWER Begin at entryway to detect unusual sounds or odors then move to center of room Use two people, divide room in half IED Search Pattern for Room - ANSWER Level One-Floor to Waist Level Two-Waist to Chin Level Three-Chin to Ceiling Level Four-Above false ceiling if required IED Search of Vehicle - ANSWER Use of K9 if available Focus on load-bearing areas LEO Safety Precautions for IED - ANSWER Anticipate secondary devices Don't use radios/cell phone/television transmitting devices