THE HEAD SNAP

It is the force of the last frontal head shot bullet that causes JFK’s backward head snap. We have no proof that the final frontal shot was from a Carcano nor do we know what bullets were used thus the following is just academic speculation as to what is possible. The numbers can be altered, within reason, as needed to fit the true results that are seen in the Zapruder film. What this proves is that it is possible for bullets from the front to cause the head snap and that no shots from the rear Sixth Floor occurred.
   The momentum of a Carcano bullet transferred to the head according to Wilber, p 222 is 1.1 feet per sec. This is 13.2 inches/sec and 0.733 inches per Z frame. [Using his numbers and recalculating the momentum is actually 1.6 ft/sec which is 19.2 inches/sec and 1.1 inches per Z frame which is about half of the actual head snap movement of 12 inches over 10 frames, Z 313-323. According to Thomson the velocity of the head snap is 1.6 ft/sec. over 8 frames, which equals 1.1 inch per Z frame.] The momentum of the bullet impact is 43 foot-pounds per second. Momentum of a particle, P = MV. Assuming: A Carcano 160 grain bullet times 1900 feet per second = 304,000 foot grains per second divided by 7000 grains (per pound) = 43 foot-pounds. A foot-pound is the energy it takes to move one pound a distance of one foot without any friction or resistance. This small energy is only half of the story. Understand that the bullet penetrated the skull striking it two times, at entry and exit. This double impact is often overlooked with the kinetic energy transfer and the work done by the bullet. The momentum of the first impact is 43 foot-pounds and the second impact is about half or 20 foot-pounds. Thus at least 60 foot-pounds of momentum exists in the bullet. JFK’s momentum is the speed of the car about 3mph or 4½ ft/sec [depending upon who calculates it] but in this study it is considered zero.
   According to Wilber the head neck mass is 34 pounds (20% of 170 lbs) but the weight of the head neck mass is not related to a percentage of body weight so this is a crude guess. Simple subtraction says that 34 pounds can be moved at least one foot [head snap distance] when acted upon by a force of 43 to 60 foot-pounds but this is not the formula for collisions. An assumption of 34 pounds for the head and neck seems extreme when the head is considered as an 9” sphere its volume is 381” cubic inches. [1 gal = 231 in³ or 3.7853 l³ with a weight of 8.3 lbs/gal.] The density of the head should approximately equal the value of water or 62.4 lb/ft³ or 1 kg/liter because the airways would cancel out bone density leaving only water to consider. A 9” sphere of water weighs 13.75 Lbs [62.4 / 1728 x 381]. JFK’s brain was weighed at an exceptional 1500 grams, which is only 3¹/₃ lbs leaving 10 lbs of bone and other tissue. If the head and neck are considered a 9” high cylinder with a 4.5” radius it has a volume of 572 in³ and it would weigh 20.6 lbs when filled with water. According to the burn formulas the head is 14% and the neck is 4% equaling 18% of body surface area. Thus 14% of 170 is 23.8 lbs but the weight of the head is not related to a percentage of body weight. Averaging 23.8 and 13.75 we get 19 lbs. Only a small part of the neck mass is involved in the head snap because the head pivots on the neck. The neck acts like a tether stopping maximum backward head movement storing potential energy from the kinetic energy and causing forward rebound movement starting at Z 324 with the release of the potential energy. Placing several persons supine with the head resting on bathroom scales resulted in an average range of 8 to 10 lbs. An assumption of 15 to 20 lbs for the head neck mass appears more realistic than 34 lbs. I suspect that mid-neck severed heads weigh about 15 lbs but I do not know of any corner studies confirming this. An accurate estimate of the head neck mass is essential to the calculations.

[Using 15 lbs, E=(½ x 15)(1.8)² = 24.3 foot-pounds, using 26.5 lbs, E=(½ x 26.5)(1.8)² = 43 foot-pounds, using Wilber’s 34 lbs, E=(½ x 34)(1.8)² = 55.08 foot-pounds required to move the head as seen in the Z film, see below.]

Momentum is only half the story of the head snap. The kinetic energy transferred from the bullet to the head must also be considered. Work of a resultant external force on a body is equal to the change in kinetic energy of the body. The energy required to accelerate a mass to a given velocity is proportional to the square of the velocity (E = ½MV²). Assume JFK’s head snap is a big 10 inches over five Z frames 313-318 for a velocity of 2 inches per 1/18 sec. or 3 ft/sec. E=(½x34)(3)²= 153 foot-pounds of energy required to do the work of moving JFK’s 34 lbs head. According to Lifton, p 49, JFK’s head moved forward or clockwise rotation two inches between frames 312 and 313. This is consistent with the Parkland occipital wound occurring about 310-311. The .45 cal. wound occurs about 311-313 but it is not discernable in the film. The last shot occurs between 312 and 313 and head then snaps backward and left from 313 to 323 and rebound forward motion starts at 324. Excess energy transferred to the head causes this rebound at 324 when the neck acts like a tether. Lifton does not give the distance traveled during the head snap but it appears to approximately equal to the top of the car window in front of Connally. Assume it to be a long distance of 1 foot. The velocity is then 12 inches per 10/18^ths sec. [313-323], which is 21.6 inches per second or 1.8 ft/sec. E=(½ x 34)(1.8)² = 55.08 foot-pounds required to do the work to move the 34 lbs head. Let us assume an extreme head snap of 12 inches in 5 frames [not seen in Z film] then 220 ft/pounds of energy is required to move the head. Edgewood Arsenal ballistic tests for the WC, Wilber p 166, 6.5 mm 160 grain Carcano tests simulating the Magic bullet:

*Energy lost from the bullet and transferred to the body

            Edgewood Arsenal was attempting to prove the magic bullet thus this data is probably misleading. Skull bones tend to fracture at about 300 ft/pounds but the skull has different thickness and curvatures thus the amount of energy to cause fractures is variable by location on the skull. Assumptions: It takes about 250 to 350 ft/pounds to fracture the skull, which is close to the rib fracture energy above. Assume the energy of the above 14 cm of the neck wound is needed to transverse the brain. Assume the energy for skull fractures is equal to the wrist.

            Kinetic energy is the force or ability to do work. Work requires the movement or displacement of objects. The kinetic energy transferred from the bullet to the body is more than enough to overcome the momentum required to do the work of moving the head backwards no matter what extreme or minimal values are used for the academic calculations of the head snap. No matter how one manipulates the numbers the bullets momentum plus kinetic energy transferred results in the work of backward head snap of one foot in [10 Z frames], 10/18^ths of a second due to a frontal headshot. The bullet would exit with about 500 foot-pounds at a speed of about 1185 ft/sec.
            Additionally the effects of the .45 cal. bullet must be considered. Momentum of a particle, P = MV. Assuming: A .45 cal. 230 grain bullet times 800 feet per second = 184,000 foot grains per second divided by 7000 grains (per pound) = 26 foot-pounds of momentum energy. The kinetic energy of this bullet [E=mv²/2g7000 or mv²/450000] is 327 foot-pounds. Assuming 319 foot-pounds for distance to JFK and to enter the skull and brain, leaves 8 foot-pounds remaining in the bullet thus the velocity of the exiting bullet would be 125 ft/sec. The streaking .45 cal. bullet seen exiting in Z 313 is moving 100 to 150 ft/sec. This speed is consistent with the math because the speed of entry is not known nor is the energy transferred known. What is known from the Zapruder film is that JFK’s head rotates a full 90º to the left at Z 316-323. Because the head freely rotates on the spinal coulomb when unconscious very little energy is required to accomplish this rotation. The head snap as seen in the Zapruder film is true and correct and consistent with two bullets to the right temple area.
           Energy to move a 34 lbs head mass as calculated above 55, 153 or 220

            Maximum Total = 1169 foot-pounds to perform the work of the head snap motion of one foot in 5/9^ths second. The work or movement of a resultant external force on a body is equal to the change in kinetic energy of the body. The excess energy results in the forward rebound movement starting at Z 324 and the movement of the exploding bone, blood and brain matter to the left rear of JFK.
            The total energy transferred from the two bullets to the head body is more than enough to overcome the momentum required to move the head backwards no matter what extreme or minimal values are used for the academic calculations of the head snap.

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