A Bullet's (lack of) Transfer Of Kinetic Energy

[Tom Gram]

55 minutes ago, Pat Speer said:

Yes, he was a brain surgeon and not a pathologist. So he was careful with his words. He didn't know what kind of ammo was used. He didn't know from where the shots were fired. But he said the wound appeared to be a tangential wound, and even mentioned this in his testimony, long after he'd been told the pathologists said it was an exit for a shot entering the back of the head.

He'd been a military surgeon and knew better. The HSCA FPP knew better as well. They went to great lengths to avoid this, of course, by pretending there was no gaping hole in the scalp as observed by Clark, Humes, and well, everybody. 

I’m generally a supporter of your work on the medical evidence, and argue in favor of your positions pretty regularly on here, but I have a really hard time with Clark. This is the top brain surgeon in Dallas - who you praise for his astute observation that the wound appeared to be a tangential wound - but your theory is heavily dependent on Clark completely forgetting the location of the wound an hour or so after looking at it. It seems a little unfair to tell people to trust Clark’s statements about a tangential wound and ignore everything he said about the wound location, observing cerebellar tissue, etc. 

Clark observed the wound directly and unequivocally told the entire world that the wound was on the back of JFK’s head in the afternoon press conference. Your rationale for not trusting Clark is that doctors can sometimes be wrong, and that Clark publicly accepted the findings of WC i.e. he didn’t want to stand up to the entire US government. I understand why people are skeptical. It does seem like a bit of a stretch to think that a highly competent brain surgeon could screw up that massively and forget such a critical detail so quickly, but I suppose anything’s possible.

Edited November 27, 2022 by Tom Gram

[Chris Bristow]

12 hours ago, Sandy Larsen said:

If anybody ever says that a bullet couldn't have thrown Kennedy' head and torso back, consider the following thought experiment. It's based on the physics principle that every reaction has an equal and opposite reaction.

If you've ever shot a rifle, recall the amount of kick it gave your shoulder when you pulled the trigger. Now, imagine holding the rifle lightly against the forehead of a friend's head and pull the trigger. That would kick your friends head back forcefully.

That is the same amount of impact your friend's head would feel if he got hit there by the same bullet. Unfortunately, that's true only if the bullet didn't exit his head. For example, if the bullet fragmented and stayed inside.

While that experiment isn't quite applicable to the Kennedy case, it does give an idea as to what the potential impact from the bullet might have been.

 

Here's a thought experiment that IS more applicable to the Kennedy case: Super-glue a bullet to the tip of a steel rod that is the same diameter as the bullet. Drill a hole through your friend's forehead and insert the rod, bullet first, into the hole. Push the rod in till the bullet rests on the inside surface of the back of the skull. Now, imagine how hard you would have to hit the rod with a hammer in order to break a fist-sized hole through the back of your friend's head and to tear the scalp. Do you imagine that that hard of an impact would have been enough to throw your friends head back, and even his torso? I sure do.

So yes, a rifle bullet to Kennedy's head could have, and did, throw it and Kennedy's torso back.

 

I have a different take on the force you feel in the shoulder when firing a rifle. Maybe someone with a deeper understanding of physics will have a better explanation.
At the first moment the bullet is separated from the shell it is no longer in contact with the rifle and does not add to the kick in the shoulder. At that 1st moment the bullet only has the energy acquired from the powder in the shell and has not been accelerated by the expanding gas yet.
 I think the rifle kick is due to the expanding gasses pushing in all directions. Maybe we could define that as an equal and opposite reaction or maybe the gas expanding in all directions is one force and the equal and opposite force may be from the gasses movement, I don't know. But I think either way the rifle kick is not a measure of the bullets energy as much as the expanding gasses.

[Sandy Larsen]

55 minutes ago, Pat Speer said:

3 hours ago, Sandy Larsen said:

Here are Dr. Clark's exact words, stated shortly after working on Kennedy:

"The head wound could have been either the exit wound from the neck or it could have been a tangential wound, as it was simply a large, gaping loss of tissue."

55 minutes ago, Pat Speer said:

Yes, he was a brain surgeon and not a pathologist. So he was careful with his words. He didn't know what kind of ammo was used. He didn't know from where the shots were fired. But he said the wound appeared to be a tangential wound.

 

I don't believe Dr. Clark ever said that the wound appeared to be a tangential one. He just said it could have been one. There's an important difference between those two characterizations.

 

 

[Chris Bristow]

The storm drain theory bothers me. I have heard the drain pipe goes all the way to the river which means even a small person would have a very long escape route. I think the confined area the shooter would occupy means the muzzle blast would extend out of the drain opening and be visible the the witnesses on Elm.
 If someone like Hargis saw or was alerted to the muzzle blast he would be in the drain in seconds. Once he popped the lid off and dropped into the drain he could have his gun pointing at the shooter butt as they tried to crawl away. I think the shooter would be a rat in a trap. A quick get away would be impossible. So I just wonder if a shooter would set themselves up for that slow and egress.

[Sandy Larsen]

1 hour ago, W. Niederhut said:

You can't generate a front-to-back force vector with a bullet fired from behind the limo.

 

William,

If you insert a spring into the system, you can reverse the direction of a force. It seems to me that that is what Pat is talking about. If you push a volume of fat and muscle down, it will bounce back like a spring. If you stretch a ligament out, it will pop back.

But I'm with you on this one. You can't get much spring action from body tissues.

 

[Chris Bristow]

I have seen examples of firing squads shooting people in the back of the head and sometimes the head moves toward the shooter. But which way the head moves often is dictated by the manner in which the body folds as it collapses. If the knees buckle first the knees go forward causing the torso to lean back which causes the head to flop forward from the torso moving backwards. Other times the torso breaks at the waist first. Then the torso rocks forward causing the head to flop backwards. If a person was standing sideways to the shooter a similar reaction may happen if one knee buckles before the other.
 There seems to be an immediacy to the reaction in the knees which makes me if it is  a neurological reaction or kinetic energy transferring to the knees causing them to move in the only direction they bend, or both.

Edited November 27, 2022 by Chris Bristow

[W. Niederhut]

3 hours ago, Pat Speer said:

It's called recoil. The head bounces down and then back. 

JFK was leaning his head forward clutching his throat when the fatal bullet instantaneously blew his head violently backward.  That's not recoil or a de-cerebrate reflex.   It was momentum from a frontal shot to the head.

The fatal bullet clearly didn't push his head down then back.  It blew it violently backwards from the forward leaning position JFK was in when the bullet struck him.

Edited November 28, 2022 by W. Niederhut

[Chris Bristow]

If you push the head forward how much tension is generated that would cause the head to recoil backwards? If I pull my head forward to the chest then apply a lot of pressure and let go my head bounce back an inch or two. So equal and opposite forces may still add to the movement but I don't think muscular tension or compression of the tissue and fat causes much of a reaction at all.
 Did JFK's head bounce off his chest? Reproducing the position I find my head will hit the the chest when my head is pointed down by 70 degrees. JFK had his head down by about 35 degrees. It does not look to me like his head ever came close to bottoming out on his chest.

[Lawrence Schnapf]

Bill Brown- Have you read Paul Chambers' book "head shot"? he is a physicist who explains the various laws of physics that apply to wound ballistics. This book will help round out your scientific understanding.

From an experimental standpoint, Failure Analysis conducted a demonstration for the 1992 ABA mock trial (Failure Analysis worked for both sides in the mock trial using different teams. In his book, Posner only used the part of the firm's work that was done on behalf of the prosecution). 

The CEO of Failure Analysis who was a trained marksman fired frangible bullets from a high velocity rifle into plastic jugs of water. The kinetic energy of the frangible bullets was so dissipated upon impact that none of the fragments exited the opposite of the plastic jug. 

The laws of physics are provide that the smallest particles would remain closest to the point of impact because they had relatively large surface area vs mass and could lose their momentum much more quickly. (as a former geology major this was not surprising since we know that small particles settle in quiet waters while heavier particles can settle in rougher waters. This is way clays and shales represent deep water deposition environmental while sandstones represent near show, shallow deposition environments-but I digress). 

the trail of metal metals in the autopsy x-rays show that the smallest are located near the front of the head.  This would be consistent with a frangible bullet fired from the front.        

[Sandy Larsen]

1 hour ago, Chris Bristow said:

I have a different take on the force you feel in the shoulder when firing a rifle. Maybe someone with a deeper understanding of physics will have a better explanation.
At the first moment the bullet is separated from the shell it is no longer in contact with the rifle and does not add to the kick in the shoulder. At that 1st moment the bullet only has the energy acquired from the powder in the shell and has not been accelerated by the expanding gas yet.
 I think the rifle kick is due to the expanding gasses pushing in all directions. Maybe we could define that as an equal and opposite reaction or maybe the gas expanding in all directions is one force and the equal and opposite force may be from the gasses movement, I don't know. But I think either way the rifle kick is not a measure of the bullets energy as much as the expanding gasses.

 

Chris,

I'm an electrical engineer and I've taken numerous physics courses. But I'm glad you challenged me because I realize now that I made an error in my analysis.

Here is my analysis:

When the trigger is pulled, the gunpowder is ignited and the gas in the chamber expands. It applies equal force in all direction. The radial forces all cancel, so no net force is applied to the gun barrel. The force is applied to the rear of the bullet, and an equal and opposite force is applied to the near end of the barrel. These two forces will be precisely the same -- though opposite in direction -- at all times till the bullet exits the barrel. After that there is no more force applied by the gas. Since both surfaces were acted on identically, the bullet and the gun received identical amounts of energy.

(I simplified the problem by ignoring atmospheric pressure. It would have made very little impact on the analysis.)

The gun's recoil is stopped by the shoulder, and so all of the gun's kinetic energy is transferred to the shoulder. Likewise, the bullet is stopped by the target, and so all its kinetic energy is transferred to the target.

Therefore, the shoulder and target will be hit by the same amount of energy.

I initially did the analysis in my head. It was when I wrote it down that I discover my error. The problem is that I didn't take into account that the gas is still expanding after the bullet exits the barrel. Which means that the force is still being applied to the near end of the barrel and the kick continues, whereas no further force is being applied to the bullet.

I need to kick this around for a while and see if I can come up with the real answer. Maybe you can figure it out.

The weird part is that I was just doing some research on this, and some comments I read made it sound like the kick continues on much, much longer than it takes for the bullet to exit the barrel. Which, if true, means that the bullet has just a tiny percentage of the energy that's in the kick. And that makes me wonder how the bullet could possibly do the damage it does.

 

[Pat Speer]

2 hours ago, W. Niederhut said:

JFK was leaning his head forward clutching his throat when the fatal bullet instantaneously blew his head violently backward.  That's not recoil or a de-cerebrate reflex.   It was momentum from a frontal shot to the head.

The fatal bullet clearly didn't push his head down then back.  It blew it violently backwards from the forward leaning position JFK was in when the bullet struck him.

So you're denying that the head first went down? 

[Pat Speer]

2 hours ago, Sandy Larsen said:

 

I don't believe Dr. Clark ever said that the wound appeared to be a tangential one. He just said it could have been one. There's an important difference between those two characterizations.

 

 

From patspeer.com Chapter 16b...

 

Let's revisit the words of the doctor who first inspected Kennedy's large head wound, Dr. William Kemp Clark...

Just hours after the assassination, Dr. Clark told the nation at a press conference that the wound "could have been a tangential wound, as it was simply a large, gaping loss of tissue." And from there his resolve grew stronger. Over the next few weeks, in interview after interview, Dr. Clark repeated such claims and was considered so credible that as late as December 23, 1963, Medical Tribune and Medical News was still reporting that the fatal bullet struck "a tangential blow that avulsed the calvarium and shredded brain tissue as the bullet left the skull on a glancing course."

Dr. Clark was just not one to back down. Months after he'd been told the conclusions reached at autopsy, in fact, Dr. Clark told the Warren Commission that, in his impression, the large head wound was a--drum roll, please--"tangential wound." To his eternal credit, moreover, Dr. Clark also told the Warren Commission why he suspected as much. On March 21, 1964, he testified that if a bullet “strikes the skull at an angle, it must then penetrate much more bone than normal, therefore, it is likely to shed more energy, striking the brain a more powerful blow. Secondly, in striking the bone in this manner, it may cause pieces of the bone to be blown into the brain and thus act as secondary missiles. Finally, the bullet itself may be deformed and deflected so that it would go through or penetrate parts of the brain, not in the usual line it was proceeding.” Dr. Clark had thereby testified that, in his opinion, the injury to Kennedy's brain was more extensive than would be expected if the bullet had simply entered low on the back of the head. As he only inspected the brain at the large defect, moreover, he had testified that, in his opinion, a bullet had transited the skull along the surface of this defect, i.e., that this defect did not appear to be the exit for a bullet entering elsewhere. He'd also voiced his suspicion that splinters of bone had been blown into the brain at this location.

Now, we should probably note here that Dr. Clark never really wavered from his suspicion that the wound was "tangential." While he testified to the Warren Commission that the wound could be other than a tangential wound, he only did so after being asked one of Arlen Specter's infamous leading questions...

Mr. SPECTER - The physicians, surgeons who examined the President at the autopsy specifically, Commander James J. Humes, H-u-m-e-s (spelling); Commander J. Thornton Boswell, B-o-s-w-e-l-l (spelling), and Lt. Col. Pierre A. Finck, F-i-n-c-k (spelling), expressed the Joint opinion that the wound which I have just described as being 15 by 6 mm. and 2.5 cm. to the right and slightly above the external occipital protuberant was a point of entrance of a bullet in the President's head at a time when the President's head was moved slightly forward with his chin dropping into his chest, when he was riding in an open car at a slightly downhill position. With those facts being supplied to them in a hypothetical fashion, they concluded that the bullet would have taken a more or less straight course, exiting from the center of the President's skull at a point indicated by an opening from three portions of the skull reconstructed, which had been brought to them---would those findings and those conclusions be consistent with your observations if you assumed the additional facts which I have brought to your attention, in addition to those which you have personally observed?

Dr. CLARK - Yes, sir.

Well, jeez Louise. Specter may as well have asked him "If the doctors said something could be black would you agree it could be black?" As Clark's acceptance of the "official" story was conditional on both Specter's false description of Kennedy's position at the time of the head shot ("with his chin dropping into his chest") and his false description of the trajectory from the entrance observed at autopsy to the large defect on the top of Kennedy's skull ("a more or less straight course"), it's clear that Clark never really agreed with what Specter was selling.

Unfortunately, he rarely spoke on the subject after his testimony. Perhaps we now know why.

I mean, it's not as if Clark's assessment could be rejected out of hand. In 20th Century Arms and Armor, published 1996, military historian Dr. Stephen Bull, while discussing the Mannlicher-Carcano rifle, defends that the rifle was capable of causing Kennedy's wounds. He asserts, not inaccurately, that the rifle was capable of being fired fast enough and with enough accuracy to kill Kennedy as proposed by single-assassin theorists. He also recites a lot of the nonsense spewed by Dr. Baden in his book Unnatural Death, and debunked in chapter 13b of this book. Where Bull really slips up, however, is in his description of the second shot to hit Kennedy. He writes: "A second shot clipped the top of the President's skull, shattering it, and broke against the front windscreen strut." The official story on this bullet, of course, is that it did not clip Kennedy's head, but pierced it, exiting only after traveling four inches or so through the brain. That Bull, having written a number of books on WWI and WWII weaponry and tactics, thinks Kennedy's large head wound was created when a bullet "clipped" the top of his head, is, one can only assume, supportive that such "clippings" do occur.

Edited November 28, 2022 by Pat Speer

[Benjamin Cole]

My two cents:

There are really smart people on all sides of "from which direction did shots come from" issue. 

I contend it is the timing of the shots that is more important, or at least less disputable. 

JBC is shot ~Z295 and JFK at Z313. That less than one second apart.

Ergo, JBC-JFK were not shot by a lone gunman armed with a single-shot bolt-action rifle.  

Secondly, there was a smoke and bang show on or near the Grassy Knoll. Whether a diversion or in earnest, that also implies a conspiracy. 

A bungled autopsy, government prevarication, evidence destruction, and perhaps some plain old-fashioned errors make determining the direction of shots...well, difficult.

The timing! A more fruitful inquiry.....

 

[Chris Bristow]

3 hours ago, Sandy Larsen said:

 

Chris,

I'm an electrical engineer and I've taken numerous physics courses. But I'm glad you challenged me because I realize now that I made an error in my analysis.

Here is my analysis:

When the trigger is pulled, the gunpowder is ignited and the gas in the chamber expands. It applies equal force in all direction. The radial forces all cancel, so no net force is applied to the gun barrel. The force is applied to the rear of the bullet, and an equal and opposite force is applied to the near end of the barrel. These two forces will be precisely the same -- though opposite in direction -- at all times till the bullet exits the barrel. After that there is no more force applied by the gas. Since both surfaces were acted on identically, the bullet and the gun received identical amounts of energy.

(I simplified the problem by ignoring atmospheric pressure. It would have made very little impact on the analysis.)

The gun's recoil is stopped by the shoulder, and so all of the gun's kinetic energy is transferred to the shoulder. Likewise, the bullet is stopped by the target, and so all its kinetic energy is transferred to the target.

Therefore, the shoulder and target will be hit by the same amount of energy.

I initially did the analysis in my head. It was when I wrote it down that I discover my error. The problem is that I didn't take into account that the gas is still expanding after the bullet exits the barrel. Which means that the force is still being applied to the near end of the barrel and the kick continues, whereas no further force is being applied to the bullet.

I need to kick this around for a while and see if I can come up with the real answer. Maybe you can figure it out.

The weird part is that I was just doing some research on this, and some comments I read made it sound like the kick continues on much, much longer than it takes for the bullet to exit the barrel. Which, if true, means that the bullet has just a tiny percentage of the energy that's in the kick. And that makes me wonder how the bullet could possibly do the damage it does.

 

I think the kickback just takes longer to spend the initial energy from the gas expanding. It has to move backwards a couple inches and push into the arm to spend its energy. The bullet on the hand has long left the barrel.

Seems to be some debate online about whether the equal and opposite reaction of the bullet moving forward causes the gun to go backwards or others say the gases expanding down the barrel cause the recoil. I can't see how a bullet could affect the kickback if it's not in contact with the rifle while moving down the Barrel. I could see it's inhibiting The Escape of the gas while it's in the barrel and that contributing to the kickback. I don't think I should speculate any further cuz it feels like I could be completely wrong in the end.

 

[W. Niederhut]

14 hours ago, Pat Speer said:

So you're denying that the head first went down? 

Pat,

     When I look at the Zapruder footage, I see JFK's head tilted forward as he clutches his throat.  Then the fatal bullet very abruptly blows his head violently backward from that forward-leaning position.  Not recoil.

     The law of conservation of momentum dictates that the bullet had to be moving at high velocity from front-to-back-- the same direction as the head (and body) post-collision.

    A mathematical equation would express this as;

m1v1 +m2v2 = m1v3 + m2v4

    where m1 is the mass of the bullet (and fragments) and m2 is the mass of JFK's head (and fragments)

     v1 is bullet velocity (pre-collision)

     v2 is JFK's head velocity (pre-collision)

     v3 is bullet velocity (post-collision)

     v4 is JFK's head velocity (post-collision