Reply #162: yeah, that's the ticket

[frogcycle]

they are just twitching

of course a 50cal is like 5 times the diameter of a 6.5 mm. disregarding greater length, that alone is fifteen times the cross-sectional area, and thus at least seventy five times the mass


the debate above over ke and momentum is long on formulae and short on simple facts

leaving out all the constants and such, ke is determined by mass times velocity squared; momentum by mass times velocity

Transfer of momentum and transfer of energy differ, but in both cases the fundamental laws of thermodynamics apply. as long as we're not talking relativity (which we're not), then conservation of momentum and conservation of energy both apply.

When a collision occurs, transfer of both momentum and energy occur, but the net of both after the collision is identical to what it was before the collision.

The mass of the projectile does not change, nor does the mass of the struck object. If the projectile passes through the struck object "cleanly" then it may retain most of its velocity. It is slowed down by friction, which converts some ke to heat, and by the amount of energy required to part the material of the struck object - break molecular bonds and deform material sufficiently to pierce the material. The shape of the projectile and the consistency of the struck object can combine to make this a pretty low amount of energy. In that case, the projectile continues on its way undamaged and only slightly slowed.

If, however, the projectile deforms or breaks up, energy is used in accomplishing that - lots of energy relative to that required to deform/break up the struck material. When it deforms/breaks up, its profile changes, and it can no longer pass through without a LOT of friction. That generates a LOT of heat, and explosive response if there is plenty of material that will vaporize upon heating.

The explosion does not go only in the direction the projectile was traveling. It goes all directions, and will follow a "path of least resistence". To the extent the deformed/broken up projectile transfers its energy of motion by "pushing" the material of the struck object, then the struck object will move in the same direction, possibly angling off somewhat (the billiard ball analogy).

In my view the fact of brain material and skull fragment going toward the back of the car does not necessarily mean the bullet came from the front. The explosion can have blown it back. There is much talk of where in fact exit wounds were, and contradictory autopsy photos, though, so it is pretty hard to reconstruct the event, lacking reliable detailed evidence. It's too easy to "cherry pick" and come up with multiple scenarios. The motion of the overall struck object, however should follow the billiard ball scenario. Much as the Taliban(?) in the video fly AWAY from the shooter, the overall motion of the head and shoulders should be AWAY from the shooter. Again, though, we don't have all the detail in reliable form. Did the driver stomp the gas upon hearing the first shot, causing the head snap that happened to correspond to the second shot? Perhaps it sounds like too "convenient" an explanation, but there was so much going on, so many inputs/outputs, that we can only come up with "most likely' scenarios, and every damned one of them still has questions. I am not a neurologist but I don't buy the "muscle reaction" explanation. The brain was destroyed instantly. Could it have sent a basically random-noise signal to jerk back as part of its demise? Sounds too "convenient" an explanation. Why not a signal to throw your hands up, to leap forward, whatever. The motion of the head, to me, was motion imparted by outside force (bullet, car motion, ??), NOT a spasm of the body.

I asked elsewhere why the headshot was so destructive and the "magic bullet" so "clean". Presumably same ammunition, right? Is the skull sufficiently resistive to initiate deformation/fragmentation, whereas the torso/neck, connolly's torso/rib, hand, and thigh were all sufficiently soft so that bullet just sort of glided to a stop? Also a rather "convenient" explanation of a seeming contradiction. But possible, I suppose.