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Walter A. "Butch" Kennedy

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Conservation of linear momentum using vector sum analysis
W. A Kennedy  More Info
Impact velocity from conservation of linear momentum for the traffic accident investigator and reconstructionist: A manual on deriving and using the speed-at-impact ... equations with the 360 degree method
W. A Kennedy  More Info

About the Jacksonville Sheriff's Office

The Jacksonville Sheriff’s Office “is unique in that the law enforcement agency is an integral part of the City of Jacksonville. In 1968, the City of Jacksonville consolidated with Duval County to form one governing body. The Jacksonville Police Department and the Duval County Road Patrol combined to create the Jacksonville Sheriff’s Office. Because of this consolidation, JSO is led by an elected sheriff and provides law enforcement to the community, detention for law breaking individuals and also prevention programs through community policing, community affairs and the Police Athletic League.”


The Jacksonville Sheriff’s Office employs approximately 1,600 police officers, 700 correctional officers and 700 civilian personnel in five departments: Department of Patrol and Enforcement; Department of Investigation and Homeland Security; Department of Police Services; Department of Personnel and Professional Standards; and the Department of Corrections.


The patrol function of the Jacksonville Sheriff’s Office falls under the direction of the Department of Patrol and Enforcement.  It is divided between Patrol Division East (Zones 1, 2, and 3) and Patrol Division West (Zones 4, 5, and 6).  Police Officers assigned to the Patrol Divisions are the "first responders" to a call for police service.  Patrol is generally considered the backbone of a police agency, not only because it is the largest component of the organization but also due to the variety of calls the officers handle.  The Police officers respond to reports of crime, conduct traffic control and enforcement, perform many community policing functions and contribute to the investigative role through diligent follow-up.  Each Patrol Division is directed by a chief.


The Jacksonville Sheriff's Office Department of Corrections is made up of 686 certified corrections officers and civilian personnel and encompasses three correctional facilities for the secure, humane, corrective and productive detention of individuals incarcerated in Duval County. The largest of these facilities is the John E. Goode Pretrial Detention Facility (PDF) located in downtown Jacksonville, adjacent to the Police Memorial Building and conveniently located near the Duval County Court House. A state-of-the-art facility when opened in April 1991, the PDF is a twelve-story building with an inmate capacity of 2,189. All individuals arrested in Duval County pass through the portals of the PDF where they are booked on their criminal charges. Prior to a first appearance hearing many individuals will be released through various legal avenues. Individuals not eligible for release will be housed at PDF until disposition of the criminal charges.




Walter A. “Butch” Kennedy served in the US Army from 1965 to 1968.  Shortly after his discharge he joined the Jacksonville Sheriff’s Office (Florida).  During his 17 year law enforcement career he has worked patrol, traffic and training.  In 1983, he was awarded a Medal of Merit for Bravery.  Between 1986 and 1992, he was a full-time instructor at the Institute of Police Technology and Management (Florida).  Walter Kennedy is the author Conservation of Linear Momentum Using Vector Sum Analysis and Impact Velocity from Conservation of Linear Momentum for the Traffic Accident Investigator and reconstructionist.


According to the book description of Conservation of Linear Momentum Using Vector Sum Analysis, it “is difficult for even the experienced reconstructionist to visualize the momentum components of colliding vehicles. To conquer this problem, W. A. Kennedy has drawn a series of “pictures” that present a graphic solution to the momentum equations. In this book, the author uses a coordinate system to graphically illustrate the vector components of the vehicles involved. To clarify the graph, he uses a distinct color for each vehicle and provides an explanatory text, complete with the momentum formulas and all of the variables needed, to solve the problem.


The graphical solutions provide an alternative to formulas in determining pre-impact and post-impact vehicle speeds. They also provide a check on the accuracy of computations that use formulas and enable the crash reconstructionist to gain a clear visual impression of the vector components present in collisions. After a brief introduction, Mr. Kennedy addresses the following topics: Post-Collision Scene Data and Trajectory Analysis Using the Right Hand Coordinate System; Vectors and Vector Analysis; Post Impact Analysis Pre-Collision Scene Data and Trajectory Analysis; Pre-Collision Side of Equation; Post-Collision Data; and, Trajectory Analysis Using the Left Hand Coordinate System

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