What physics reveals about the JFK event

[Andrew Mason]

Jet Effect.

Hi John.   The coconut shot is very good.  It certainly shows the jet effect.  Do you know what ammunition was used?   It is rather easy to duplicate with hunting bullets (no jacket) but much more difficult with jacketed ammunition.  The coconut might be hard enough to deform a jacketed bullet. 

[Matt Grantham]

The right side of JFK's skull opened.  His head was also turned to the left and he was leaning to the left. 
How do you know this if you have not worked it out?  See my earlier post using 100 grams of matter being ejected with 10% of the bullet energy. That is enough to send the head recoiling at 1 m/sec.

 You are willing to admit there are two forces at play right. any jet effect and the conservation of momentum? In other words any amount of force actually absorbed by the skull that is not blown out works to move the head forward. Is that in your calculation


 Did Alvarez allow for any consideration for the conservation of momentum in  his equations for JFK's head shot?

[Matt Grantham]

You must be working for Lockheed Martin on the next generation of jet engines. Your theory is that the less restricted the nozzle opening of a jet engine, the greater the acceleration.

Not at all. Just the likelihood of a small diameter cavity producing a very high pressure jet versus he likelihood of a larger one. Again demonstrate either.[/list]

[Matt Grantham]

While acknowledging the jet effect exists the examples by JM are flawed. Water container cut in half with some water remaining in the left side of the container with a projectile moving from left to right are going to fall to the left from simple gravity

[Andrew Mason]

You are willing to admit there are two forces at play right. any jet effect and the conservation of momentum? In other words any amount of force actually absorbed by the skull that is not blown out works to move the head forward. Is that in your calculation

Jet effect illustrates conservation of momentum.  Jet effect and conservation of momentum are not two different principles. Force is not absorbed by the skull.  A force is applied to the skull by the incoming bullet and moves the head forward. That forward momentum of the head, however, is overcome by the much greater rearward recoil momentum from the explosive head wound experienced by the skull (and body to which it is connected). The forward momentum imparted by the incoming bullet to the entire head, including the contents that are spewed from the head.  So that momentum adds to the momentum of the ejected contents and reduces the rearward recoil momentum of the intact part of the head and body.  But the thing to keep in mind is that the forward momentum of the exploding contents due to the release of a small portion of the bullet energy (pressure x volume = energy) is much greater than the original momentum of the incoming bullet. So the jet effect is more than enough to completely counter the incoming bullet momentum.

Did Alvarez allow for any consideration for the conservation of momentum in  his equations for JFK's head shot?

Absolutely he did (from his paper which is reproduced at 1 HSCA 434):

"I concluded that the retrograde motion of the President's head, in response to the rifle bullet shot, is consistent with the law of conservation of momentum, if one pays attention to the law of conservation of energy as well, and includes the momentum of all the material in the problem.  The simplest way to see where I differ from most of the critics is to note that they treat the problem as though it involved only two interacting masses: the bullet and the head.  My analysis involves three interacting masses, the bullet, the jet of brain tissue observable in frame 313, and the remaining part of the head. It will turn out that the jet can carry forward more momentum than was brought in by the bullet, and the head recoils backward, as a rocket recoils when its jet fuel is ejected."

[Andrew Mason]

Not at all. Just the likelihood of a small diameter cavity producing a very high pressure jet versus he likelihood of a larger one. Again demonstrate either.[/list]

Actually, a small nozzle produces a high energy, low pressure flow.   This is an illustration of Bernoulli's law, which is based on conservation of energy:  higher kinetic energy of the flow results from conversion of pressure energy (potential energy) into kinetic energy.  The jet is the result of high pressure behind the nozzle/opening.  The narrower opening causes the pressure energy to be transferred to smaller amount of matter so that matter gains more kinetic energy.

[Matt Grantham]

Actually, a small nozzle produces a high energy, low pressure flow.   This is an illustration of Bernoulli's law, which is based on conservation of energy:  higher kinetic energy of the flow results from conversion of pressure energy (potential energy) into kinetic energy.  The jet is the result of high pressure behind the nozzle/opening.  The narrower opening causes the pressure energy to be transferred to smaller amount of matter so that matter gains more kinetic energy.

Very good. High speed as opposed to high pressure. I assume you added this as a curiosity or just a well meaning correction as opposed to anything relevant to the argument at hand?[/list]

[Matt Grantham]

Jet effect illustrates conservation of momentum.  Jet effect and conservation of momentum are not two different principles. Force is not absorbed by the skull.  A force is applied to the skull by the incoming bullet and moves the head forward. That forward momentum of the head, however, is overcome by the much greater rearward recoil momentum from the explosive head wound experienced by the skull (and body to which it is connected). The forward momentum imparted by the incoming bullet to the entire head, including the contents that are spewed from the head.  So that momentum adds to the momentum of the ejected contents and reduces the rearward recoil momentum of the intact part of the head and body.  But the thing to keep in mind is that the forward momentum of the exploding contents due to the release of a small portion of the bullet energy (pressure x volume = energy) is much greater than the original momentum of the incoming bullet. So the jet effect is more than enough to completely counter the incoming bullet momentum.
Absolutely he did (from his paper which is reproduced at 1 HSCA 434):

"I concluded that the retrograde motion of the President's head, in response to the rifle bullet shot, is consistent with the law of conservation of momentum, if one pays attention to the law of conservation of energy as well, and includes the momentum of all the material in the problem.  The simplest way to see where I differ from most of the critics is to note that they treat the problem as though it involved only two interacting masses: the bullet and the head.  My analysis involves three interacting masses, the bullet, the jet of brain tissue observable in frame 313, and the remaining part of the head. It will turn out that the jet can carry forward more momentum than was brought in by the bullet, and the head recoils backward, as a rocket recoils when its jet fuel is ejected."

  I never said the conservation of momentum and the jet effect are two different principles but rather that they are antagonistic to one another in the given circumstance at hand There are indeed two competing variables. Lets use the illustration of a head shot where no exit wounds or blood splatter of any meaningful amount exits the skull. In such a situation we can conclude the force of the bullet has been absorbed, or if you prefer the language of the physicist, transferred to the skull. The transference of the that force occurs both in terms of internal damage to the skull and the the movement of the skull and body in accord to the law of conservation of momentum

 It looks like Tony Szamboti focuses on the major error behind Alvarez's equation here


The temporary
cavity pressure generated in the wake of a projectile’s path through an encased fluid filled
volume is not directly related to the shock wave momentum forward of the projectile in the
way the forward acting pressure of a jet engine is related to the momentum of its exhaust.