A Simple Question in Physics

[Gerry Down]

Most witnesses heard BANG ... ... ... BANG ... BANG.

“There was a longer pause between the first and second shots than there was between the second and third shots,” testified mayor Earle Cabell

Senator Ralph Yarborough recalled, “ . . . to me there seemed to be a long time between the first and second shots, a much shorter time between the second and third shots.”

Which it seems to me is fairly accurately portrayed in the Zapruder film. A shot from behind, momentarily moving the head forwards, and another shot from the fence/wall location sending the head backwards/to the left.

This has been well established. There was an "echo" on the head shot for some reason. And obviously Oswald could not have fired two shots in such rapid succession.

Its never been explained why there was an "echo" on the head shot but not on any of the other shots.

[Joe Elliott]

This has been well established. There was an "echo" on the head shot for some reason. And obviously Oswald could not have fired two shots in such rapid succession.

Its never been explained why there was an "echo" on the head shot but not on any of the other shots.

There is at least one rather good explanation. “Crack-Thump”.

A supersonic bullet does not make one noise. It makes two. “Crack-Thump”.

Interruption: Yes, but why not “Crack-Thump . . . Crack-Thump . . . Crack-Thump”.
Answer: I’ll get to that.

The “Crack” is from the supersonic bullet. The “Thump” is from the muzzle blast. The “Crack” travel’s most of the way, if an observer is near the trajectory of the bullet, like along the street, as most witnesses were, at the speed of the bullet, an average speed of 2,000 feet per second. The “Thump” travels at a slower speed, the speed of sound, 1,125 feet per second.

For the first shot, at a distance of 130 feet, the bullet will arrive after (velocity = distance / time, and time = distance / velocity) 130 / 2000 or 65 milliseconds. An observer may hear it shortly after that.
The muzzle blast travels 130 feet in 113 milliseconds. The difference is 48 milliseconds.

If one does the math, one finds that the theoretical time difference between the “Crack” and the “Thump” is:

First shot at z153: 48 milliseconds.
Second shot at z222: 70 milliseconds.
Third shot at z313: 98 milliseconds.

The delay between the “Crack” and the “Thump” is twice as long for the third shot than it is for the first shot. And a good deal longer for the third shot compared to the second.

Now, the exact delay will depend on the location of each witness, and will vary from witness to witness. But in general, the interval between the “Crack and the “Thump” will be greatest for the third shot. So, it may be that for the first and second shots, the “Crack” and the “Thump” arrived too close to each other to distinguish them as two separate sounds. But the third could be distinguished as two separate sounds.


Another factor is the alertness of the witnesses. After the second shot, when both the President and Governor were wounded, most witnesses did not realize that shots had been fired. Most continued clapping their hands, as can be seen in the Zapruder film. So, they might ignore the detail of what might be a backfire, like whether it was a “bang” or “bang-bang” as they concentrated on their few seconds of seeing the President and First Lady close at hand. But the third shot, with the head explosion, may cause them to become instantly alert and remember with more detail the sounds that had just occurred.


Finally, while there was an extra sound with the first shot, striking the street, there was no extra sound with the second bullet, which passed through mostly the soft tissue of the President and the Governor. In contrast, the third shot had extra sounds caused by:

•   The shot hitting at almost 1900 feet per second the skull.
•   The sound of a fragment hitting the windshield.
•   The sound of another fragment hitting the chrome windshield frame.


So, there are some extra possibilities why a witness might be more likely to mistake the third shot as two shots occurring almost together.

[Michael Carney]

My take on it is he was hit simultaneously by two bullets to the head, one from the front and one from the back. I recall seeing on one of the threads that showed the inside of the skull with fragment spray in two areas of the skull, front and back.

[John Iacoletti]

So, there are some extra possibilities why a witness might be more likely to mistake the third shot as two shots occurring almost together.

Wouldn't that witness have heard more than three of these sounds then?

[Chris Bristow]

Reading the witness statements I was impressed how knowledgeable Texans are about guns and ballistics. Many of them noted the difference between the shock wave and muzzle blast. The majority of the witnesses only heard three shots even though each shot created 2 sounds. If echos or other sounds had caused confusion we would not have the majority reporting 3 shots in total.
 Officer Smith was standing at the East side of the Elm/Houston intersection and heard many echos. It was likely the echos bouncing Eastward between the building along Elm. Two other witnesses in the courthouse facing Main St also heard multiple echos also likely to be sound bouncing Eastward down Main St.
One of the SS agents in the Queen Mary said they was a very loud echo from the underpass at the 3rd shot. He stated that the echo made it hard to determine the direction of the shot. However this could be a separate single shot from the knoll not an echo.
 So a few people heard echos based on their location yet the majority heard only three shots. I think the witnesses being educated on firearms could be why they did not report more than 3 shots.
If there was a 4th shot it could have easily occurred so close to the 3rd shot that most would not recognize it as a separate shot. The knoll is about 300 feet from the TSB and the south knoll is about 600 feet from the TSB. So if 2 shots were fired within 1/3 of a second there would be locations in the plaza where the witnesses would have heard those two shot as one. If two shots happened simultaneously then the witnesses located 1/2 way between the 2 shots would hear them as one.
 I think witnesses in the limo had the advantage of hearing the round come zinging into the limo and also heard the rounds land. So when Kellerman said the last rounds came in "as a flurry of rounds" (He conceded that the "Flurry" could have been just 2 rounds, but they are still too close together to be from the bolt action Carcano) and Greer Used the term "Almost simultaneously". it is compelling evidence of the last two shots being almost simultaneous.

[Michael Carney]

Counting shots again:

1.   Ricochet bullet off the pavement frags hitting JFK in the back of the head. Witnessed by a bookkeeper from the TSBD and several others. JFK said “my god, I’ve been hit”. Maybe frame 214 behind the sign.

2.   JFK front throat wound – judged an entry wound by a nurse with considerable experience which had to have come from the front. This is behind the sign.  Maybe frame 223

3.   JFK back wound –at which time he leans forward grabbing his chest. Maybe frame 260

4.   Grassy knoll JFK head shot – so many witnesses said a bullet came from the grassy knoll. Maybe frame 313

5.   JFK Hickey head shot – Jean Hill saw men in plain clothes shooting back. I think 4 & 5 were almost simultaneous, thus the echo? Connolly starts to turn back around while JFK is holding his throat. Then JFK lowers his hands to his chest, Connolly is almost straight forward and JFK gets hit in the head. Maybe frame 313.

6.   Connelly back wound –  If you study the Z film Connolly is still turning, hat in hand, when JFK’s head explodes. He wouldn’t be holding his hat with a shattered wrist. Connolly testified that he was complexly turned around and about to turn and look over his left shoulder when he was hit. Maybe frame 324.

Watch the Z film in slow motion and see for yourself

So with JFK grabbing his throat in maybe frame 223 and Connolly getting hit in the back at about frame 324 there are 100 frames that had elapsed between both shots. So they did not get hit by the same bullet.

[John Tonkovich]

Counting shots again:

1.   Ricochet bullet off the pavement frags hitting JFK in the back of the head. Witnessed by a bookkeeper from the TSBD and several others. JFK said “my god, I’ve been hit”. Maybe frame 214 behind the sign.

2.   JFK front throat wound – judged an entry wound by a nurse with considerable experience which had to have come from the front. This is behind the sign.  Maybe frame 223

3.   JFK back wound –at which time he leans forward grabbing his chest. Maybe frame 260

4.   Grassy knoll JFK head shot – so many witnesses said a bullet came from the grassy knoll. Maybe frame 313

5.   JFK Hickey head shot – Jean Hill saw men in plain clothes shooting back. I think 4 & 5 were almost simultaneous, thus the echo? Connolly starts to turn back around while JFK is holding his throat. Then JFK lowers his hands to his chest, Connolly is almost straight forward and JFK gets hit in the head. Maybe frame 313.

6.   Connelly back wound –  If you study the Z film Connolly is still turning, hat in hand, when JFK’s head explodes. He wouldn’t be holding his hat with a shattered wrist. Connolly testified that he was complexly turned around and about to turn and look over his left shoulder when he was hit. Maybe frame 324.

Watch the Z film in slow motion and see for yourself

So with JFK grabbing his throat in maybe frame 223 and Connolly getting hit in the back at about frame 324 there are 100 frames that had elapsed between both shots. So they did not get hit by the same bullet.

Do you have some actual evidence to back up these ideas?
If so, please produce.
Thx.