Would A Bullet Really Knock You Backwards? DEBUNKED

[Joe Elliott]

Would A Bullet Really Knock You Backwards? DEBUNKED

At around the 2:56 mark, the narrator states:

"only results in a backwards motion of 80 kg target body of 0.01-0.18 m/s,"

Or, to units readers may be more familiar with:

"only results in a backwards motion of 176 pound target body of 0.02-0.40 mph,"

President Kennedy's head backwards motion, at it's maximum speed, at frame z318, was 1.9 mph. Much faster than one would expect from any plausible weapon. But well within the capabilities of JFK's own muscles, if the bullet triggered a Neurological Spasm, which is immoral to demonstrate with humans but can and has been shown in films of animals, like that of the goat in the 1947 U. S. Army tests.

Of course, a more powerful weapon, like an anti-tank gun (equipped with a silencer, do doubt ), could, in theory push JFK's head backwards at that speed. But there are multiple problems, even with that:

1. Most fundamentally, a push from a bullet or a shell would give an almost instant impulse to JFK's head, pushing JFK's head with constant momentum. Resulting in an initial fast speed (that momentum being used to push the head alone) followed by a slower speed (the same momentum pushing both the head and torso). Instead, what is measured in the Zapruder film by Physics graduate student William Hoffman, is a slow initial speed backwards, that gradually builds up, 4 frames later, to 1.9 mph.

2. As pointed out, a weapon that powerful would splatter the whole head, not just part if it, in many directions. There would be no head left afterwards.

3. Also, a bullet, or a shell, would only pass on some of it's momentum, not all of it, as the projectile would pass through the head and continue with most of it's momentum.

But, with most people not understanding simple Classical Physics, the "Back and to the Left" argument should still continue to hold great sway over the masses.

[Michael Walton]

Yes, they do. I used to have a video clip of a guy who accidentally got shot from the front with a rifle. He was just walking and clapping when his friend's gun went off. The gun was positioned in front of and slightly to the side of him. As soon as the bullet hit, his head was thrown backward and he collapsed onto the ground. So yes, it does happen.

[Joe Elliott]

Yes, they do. I used to have a video clip of a guy who accidentally got shot from the front with a rifle. He was just walking and clapping when his friend's gun went off. The gun was positioned in front of and slightly to the side of him. As soon as the bullet hit, his head was thrown backward and he collapsed onto the ground. So yes, it does happen.

What was the type of the rifle?
What was the type of the bullet?
Most importantly, what was the mass and the velocity of the bullet?
At what speed did the victim's head move backwards?

In other words, is there an anomaly here? Does the head move backwards with more momentum than the bullet?

If not, there is nothing to explain. Once again, we would have proven that the laws of physics hold. That people are not flung away from bullets with more momentum than a bullet carries.

If there is an anomaly here, one would need to look into other possibilities. JFK was not instantly killed by the bullet that struck him in the head. He still had weak breathing and a weak heartbeat for up to 20 minutes after being shot. Martin Luther King was not instantly killed by the bullet that struck him in the head.

Is it possible the victim in this case was not killed instantly?

If so, is it possible that it was it was the victim's own muscles that propelled him backwards? There is a flash of light, There is a loud sound. A person who is not killed outright, or even totally missed, might instinctively jerk their head backwards away from the rifle. And with more momentum than that carried by the rifle bullet.

And, it is also possible that the rifle bullet went directly through the brain, which, just like JFK, could cause his head and torso to be flung back with more momentum than a bullet, due to a bullet generated neurological spasm. Regardless of whether he was shot from the front, or behind, we would see the stronger muscles of his body move the head and torso backwards, if a neurological spasm occurred.

We need to more information before we conclude that:

1. Rifles cause a victim to move backwards with more momentum than the bullet carries. Seemingly being a special exception to Newton's Laws of Motion.

or:

2. There are weapons out there where the projectile carries enough momentum to push and torso back at 1.9 mph, as seen in the Zapruder film, without totally blowing off the head.

You have not provided that information. Instead, you only bring a story.

[Andrew Mason]

What was the type of the rifle?
What was the type of the bullet?
Most importantly, what was the mass and the velocity of the bullet?
At what speed did the victim's head move backwards?

In other words, is there an anomaly here? Does the head move backwards with more momentum than the bullet?

If not, there is nothing to explain. Once again, we would have proven that the laws of physics hold. That people are not flung away from bullets with more momentum than a bullet carries.

It depends also on whether the bullet exited and, if so, at what speed.

In the case of  6.5 mm 10 g (.01kg) jacketed bullet at 2000 fps (610 m/s) the maximum momentum transfer is p=.01x610=6.1 kg m/sec. For a 61 kg person on a frictionless surface, absorbing the entire bullet momentum (no bullet exit), the person would move .1m/s or 10 cm/sec, which is not much really. If it hit the head, the head would move much more rapidly. A 6.1 kg head would move 1 m/s or 5 cm (2 in.) in 1/20th of a second. One sees this kind of movement in the z film between frames 312 and 313.

If the bullet energy causes matter to explode from the exit wound due to pressure build-up in the body/head, the momentum of the ejected matter could easily exceed the forward momentum imparted by the bullet.  In that case the body/head would recoil in the opposite direction to the ejected matter.  That is consistent with what is seen in the zfilm as the head recoils immediately after z313 and the body follows.

And, it is also possible that the rifle bullet went directly through the brain, which, just like JFK, could cause his head and torso to be flung back with more momentum than a bullet, due to a bullet generated neurological spasm. Regardless of whether he was shot from the front, or behind, we would see the stronger muscles of his body move the head and torso backwards, if a neurological spasm occurred.

I don't think this has ever been documented as a real thing.  There are many films of people being shot in the back of the head and they just fall over unconscious if not dead.

1. Rifles cause a victim to move backwards with more momentum than the bullet carries. Seemingly being a special exception to Newton's Laws of Motion.

There is, of course, no exception to the law of Conservation of Momentum which goes beyond Newton and applies to all of physics since Newton (eg Electromagnetism, Relativity and Quantum Mechanics).  Conservation of momentum was, for example, how the neutron and neutrinos were discovered. 

[Dan O'meara]

Would A Bullet Really Knock You Backwards? DEBUNKED

The video posted in the OP has no bearing on JFK's head-shot.
JFK's head explodes as a result of the shot. Pieces of his skull are blown in various directions. Jets of material, possibly brain matter and skull, are seen emanating from the top of his head. The top of his head literally blows off as a result of the shot.
To imagine there is no significant transfer of momentum from the bullet to the head in this instance is ludicrous.
The force required to achieve this incredible amount of damage would surely be reflected in how JFK's head moves as a result of this impact.

Neurological spasm and the jet effect are unnecessary contrivances when coming to explain the "back and to the left" movement of JFK as a result of the head-shot.
Good, old-fashioned physics is more than sufficient.

[Andrew Mason]

Neurological spasm and the jet effect are unnecessary contrivances when coming to explain the "back and to the left" movement of JFK as a result of the head-shot.
Good, old-fashioned physics is more than sufficient.

?? How is "jet-effect" not "good old-fashioned physics"? It is just conservation of momentum. Alvarez did not go beyond Newton's laws in explaining it.

[Joe Elliott]

It depends also on whether the bullet exited and, if so, at what speed.

Correct.

In the case of  6.5 mm 10 g (.01kg) jacketed bullet at 2000 fps (610 m/s) the maximum momentum transfer is p=.01x610=6.1 kg m/sec. For a 61 kg person on a frictionless surface, absorbing the entire bullet momentum (no bullet exit), the person would move .1m/s or 10 cm/sec, which is not much really. If it hit the head, the head would move much more rapidly. A 6.1 kg head would move 1 m/s or 5 cm (2 in.) in 1/20th of a second. One sees this kind of movement in the z film between frames 312 and 313.

Correct. The initial movement, during the z312-z313 interval, is consistent with a WCC/MC bullet striking from behind.

If the bullet energy causes matter to explode from the exit wound due to pressure build-up in the body/head, the momentum of the ejected matter could easily exceed the forward momentum imparted by the bullet.  In that case the body/head would recoil in the opposite direction to the ejected matter.  That is consistent with what is seen in the zfilm as the head recoils immediately after z313 and the body follows.

Yes and no. In theory, the "Jet Effect" could cause a 'target' to move back toward the rifle. This has been demonstrated with various targets like taped melons.

But this did not happen in the JFK murder. Because the head initially moved forward. If the "Jet Effect" occurred, JFK's head would have started moving backwards almost immediately, within 5 to 10 milliseconds of the bullet impact, because there would be no big 55 millisecond delay in the head being struck and organic material starting to move forward. We can see in frame z313 that the organic material had already started moving, right about the time the shutter closed on z312. A piece of bone, likely the 'Harper fragment', is already two to four feet away from the head in z313.

Note: The 'Harper fragment' is two to four feet from the head because z313 does not show an instant of time. When the shutter opened for z313, the fragment was two feet away. When it closed, it was four feet away.

The "Jet Effect" can occur. But in all cases, it is immediate. A taped melon doesn't move two inches away from the shooter, and then reverse directions, like seen with JFK.

I would be happy to change my mind, if someone can site a case where a 'target', like a taped melon, did reverse direction of movement due to the "Jet Effect".

I don't think this has ever been documented as a real thing.  There are many films of people being shot in the back of the head and they just fall over unconscious if not dead.

As far as I know, this never occurs in animals with subsonic handgun bullets. Only with supersonic (generally rifle) bullets.

Not going to documented in humans, because a rifle bullet strike, causing a human head to explode like the case of JFK, is too gory, too much an insult to human dignity, to be shown. This is a very strong taboo against this. CTers broke the taboo in the JFK case, but showing a film of someone else's head exploding could get you sued by their family. The only test that can be run is on animals.

There is, of course, no exception to the law of Conservation of Momentum which goes beyond Newton and applies to all of physics since Newton (eg Electromagnetism, Relativity and Quantum Mechanics).  Conservation of momentum was, for example, how the neutron and neutrinos were discovered.

Agreed. But some CTers seemed to think a 'theory' they present does not need to be explained by classical physics. There is no need for them to explain how a bullet striking from the front could cause JFK's head to initial move forward, then start to move the head backwards, gradually increasing momentum from z313 through z318, reaching the maximum speed at z318. They seem to feel that classical physics can be ignored.

The only theory that explains this movement is the 'Neurological Spasm' theory.

[Joe Elliott]

Neurological spasm and the jet effect are unnecessary contrivances when coming to explain the "back and to the left" movement of JFK as a result of the head-shot.
Good, old-fashioned physics is more than sufficient.

Well, good, I finally have someone to talk over 'old-fashioned physics' with.

How to you explain the motion of JFK's head, during z312-z318. This motion is detailed in Josiah Thompson's book "Six Seconds in Dallas", not by Josiah Thompson but by Physics graduate student William Hoffman. In Hoffman's data:

from z312-z313: The head moves forward at 2 mph.
from z313-z318: The head starts to move backwards, gradually moving faster and faster, reaching a maximum speed of 1.9 mph at z318.

How does a frontal shot explain this?
Why would it cause an initial movement of the head forward?
And when the backward movement starts, why does the speed gradually accelerated? Why wouldn't the bullet passing through the head transfer all it's momentum with 1 to 2 milliseconds, but instead transfer it's momentum over the course of 200 milliseconds?

By the way, the acceleration of the limousine does not explain this. William Hoffman, back in 1966, was way ahead of everyone. He also plotted the speed of the limousine and the acceleration of the limousine is not even a tenth of the amount of accelerated needed to explain the backwards movement of JFK's head.

 * * * * *

Also, it is not proper science, when looking into a problem to declare some theories are 'unnecessary contrivances' and should not be considered. "The theory of Continental Drift is an unnecessary contrivance, and must not be considered a possible explanation for why an animal specie from the distance past appears to have been on both sides of the Atlantic, now separated by thousands of miles".

And so it is not proper science, when looking into a problem to declare:

1. A shot from the front, is an unnecessary contrivance to explain the movement of JFK's head.
2. The 'Jet Effect', is an unnecessary contrivance to explain the movement of JFK's head.
3. The 'Neurological Spam', is an unnecessary contrivance to explain the movement of JFK's head.

All three theories must be considered. And since only the "Neurological Spam' theory explains the movement of JFK's head, it is the theory that should be accepted as the one most probably true. Unless future data collected requires a reassessment". Like video of a taped melon reversing direction. Or video of a bullet striking a target and causing the target to gradually accelerate over the course of 200 milliseconds, or a fifth of a second. But until such a time, the "Neurological Spam' theory is the one I am going to go with.