1˳ Introduction
U˳S˳ President John F˳ Kennedy was assassinated while riding in an open limousine within a motorcade through the city of Dallas, Texas on Friday, 22 November 1963˳ President Kennedy had appeared in countless such motorcades routinely during his presidency˳ The Dallas motorcade had proceeded without incident up until the end of the route when the President was suddenly shot twice by a sniper˳ Prior to the arrival of the motorcade, a local civilian named Abraham Zapruder had positioned himself on a 4 foot concrete abutment in the green space known as Dealey Plaza with his state-of-the-art Bell & Howell 8-mm “Zoomatic” color home-movie camera to film the President from a perfect elevated vantage point [1, p˳ 11]˳ Shortly after he began filming, he was startled to hear a gunshot, and seeing the President raise his arms, he first thought that the President was morbidly play-acting being shot [2, p˳ 571]˳ Mr˳ Zapruder kept filming while another shot rang out, this one fatally wounding the President in the head˳ Zapruder would thus both inadvertently and fortuitously record the entire ≈8 second sequence of tragic events on film˳
The film was initially withheld from the public (given the disturbing graphic violent content), but it was utilized as evidence by the U˳S˳ Federal Bureau of Investigation (FBI) as well as a Presidential Commission established by Executive Order by President Lyndon B˳ Johnson and headed up by Supreme Court Chief Justice Earl Warren (thus informally known as the “Warren Commission”)˳ The bipartisan Warren Commission (or WC for short) was necessitated after the primary (and only) suspect in the crime, a local man named Lee Oswald, was himself murdered two days later by a local vigilante named Jack Ruby˳ Based on its investigation, the WC would determine in 1964 from the available evidence that Lee Harvey Oswald was the lone assassin, firing three shots from the sixth-floor southeast (SE) window of the Texas School Book Depository (TSBD) building˳ The Commission considered the question of a conspiracy, but ultimately found no compelling evidence of one [3, p˳ 374]˳ Three additional independent U˳S˳ federal government investigations would affirm the WC’s basic findings [4, pp˳ 369-381], [5, pp˳ 50-58], along with other non-government investigations˳ In spite of the overwhelming physical and circumstantial evidence presented in these investigations,1 conspiracy conjectures have proliferated in the decades since [6], [4], [5], some out of genuine inquiry concerning a plethora of apparent irregularities in the investigation [7] and “oddities” in the Commission’s findings˳
Among these oddities were counterintuitive behaviors and anomalies perceived by WC “skeptics” within the now-famous “Zapruder Film˳” However, it was not until a bootleg copy of the film was aired on national television (ABC’s Goodnight America, hosted by Geraldo Rivera) in March 1975, that a stir was created among the mainstream American public [4, p˳ 371], [1, pp˳ 69, 261]˳ The stir it created is not surprising, given the sequence of events depicted in it, namely the graphic violence, especially the depiction of a fatal wound to the head caused by a high-powered military rifle bullet, something that ordinary citizens would not have had an inkling about in that era˳ But in particular, the hosts of the program (including Rivera) were adamant about bringing attention to the President’s “back and to the left” movement immediately after being shot, making an unjustified claim that this was “consistent with a shot from the front” (which echoed the assertions of early WC skeptics [8], [9]), in defiance of the other far more definitive evidence that had been made available to the public in the WC Report˳ Responding to such claims, the illustrious Nobel-prize winning physicist Luis W˳ Alvarez would shortly thereafter publish his own analysis of the Zapruder Film [10]˳ Prof˳ Alvarez examined a number of different questions being posed at the time, including the number of shots (based on jiggle analysis), the shutter speed of the camera, and the President’s reaction to the fatal shot˳ On the latter question, he concluded that the puzzling backward lurch was the result of a recoil effect (commonly referred to as “the jet effect”); this conclusion has been backed up by subsequent independent experimental studies [11], [12], [13]˳
In the current paper, the physics surrounding the shot that struck President Kennedy in the head (near-instantly killing him) will be examined in considerably more detail˳ Figure 1 shows an overview of the Dealey Plaza crime scene (using Google Earth Pro), including the locations of Mr˳ Zapruder, the Presidential Limousine (or limo), the sniper’s nest, and the trajectory of the shot, which was fired at an approximate distance of ≈81 m (266 feet)˳ The weapon purportedly used was an Italian military Carcano Fucile di Fanteria (infantry rifle), Modello 91/38 (Model 1891/1938), manufactured in 1940 at the Royal Arms Factory in Terni, Italy˳2 This weapon fires ≈10˳5 g supersonic projectiles with a muzzle speed of 658m/s that remain highly stable in flight through air˳ The effect produced by such high-energy projectiles [14], [15] upon collision with a human head is catastrophic as has been characterized through ballistics experiments [12], [16]˳ In examining this, three separate dynamical phenomena will be considered in Section 2 that explain behaviors observed in the Zapruder Film, namely (1) the initial effect of the forces directly imparted to the target (head) by the projectile (discussed in Section 2˳1), followed by (2) the secondary effect of the directional release of explosive energy escaping the skull cavity (discussed in Section 2˳2˳1), and finally (3) the nervous system reaction to a massive wound to the brain (discussed in Section 2˳2˳2)˳
