Hi Rash,
No doubt, it was a blunt object, since the scalp wasn't broken. I suppose the head of a Maglite could, at the correct angle, also be considered blunt, just like contact with the floor or a heavy bathtub, etc. would be blunt.
The easiest way to explain what I mean about low-velocity/high-pressure is to think of a bullet wound. That's high velocity. The force of the bullet if applied equally over the area of the skull would be relatively low-pressure. The major damage is at the point of impact and to the underlying tissue (damage would also depend on the bullet caliber and mass, but ignore that factor in this explanation). Because of the high velocity, the weapon (a bullet in this case) also does a great deal of internal damage under the point of impact.
Low velocity would include, perhaps, a child falling or even pushing or shaking the child's head around, forcing it into another object. It is a relatively slow-speed method of inflicting damage. The comminuted fracture on JonBenet shows evidence of this low-velocity type event. More energy was dispersed as shown by the egg-shell fracturing of the skull because of high pressure than what is seen in the low-pressure bullet example above. The egg shell fracture could also extend in a linear fashion as in JonBenet's cranium. However, it is speed and pressure that would cause the distance the fracture traveled and the width of the fracture. In my opinion, some high pressure (or fairly high) would be needed to split the cranium to the degree and length that JonBenet's is split.
A relatively high-velocity wound with low pressure, such as swinging a golf club, would continue the damage down into the brain tissue. It would and could create a comminuted area and a fracture but the remainder of energy would likely go deep below the striking point (like a bullet) instead of traveling a great distance as illustrated by the lengthy and relatively wide fracture that extends nearly to JonBenet's right eye socket.
Of course, if there were two simultaneous or nearly simultaneous skull injuries, it is possible the two (or more) fractures "met" and gave the illusion of a one-blow 8.5" fracture.
JonBenet's scalp is not lacerated at the point of impact, the fracture widens, the fracture is 8.5" long. All that suggests, to me, that a low-velocity/high-pressure injury occurred.
BOESP,
I'm not certain what you are trying to say here. Pressure is a specific force measured over a particular area say pounds per square inch.
A measure of the motion of the object that struck JonBenet would be its
momentum which is the objects
mass multiplied by its
velocity.
This allows for different objects travelling at the same speed to impart the same amount of energy on impact.
The reason for the latter sentence is that unlike a bullet the person who whacked JonBenet would have his/her velocity limited by their human physique.
The potential energy imparted to JonBenet's skull could be approximated by working out its kinetic energy, and allowing for residual energy loss.
In physics momentum is conserved so in a head-on collision you can work out the final velocities of both objects, this can allow for a stationary body, two moving bodies etc.
JonBenet's head injury I'll assume was
not a head-on collision, neither was it
inelastic which is where the two bodies stick together, I reckon it was an example of a multi-dimensional collision e.g. she was rooted in one position, and the blow struck was from an indirect or oblique angle, so the varying components, or momenta, can be separated and resolved to arrive the final momentum.
The bottom line is that the velocity of an object delivered by a human is going to be limited by default, so comparisons with bullets are misleading, it will be the
weight of the object that will be critical, so hitting a child with a spoon which may be heavier that a bullet, will not do the same damage as a maglite or a golf-club, because they weigh more, the other critical parameter will be the angle of contact, some angles impart less energy than others, consider a boxer punching his opponent's face, different angled blows are not as powerful, e.g. in general same mass, same velocity, different angle.
So the maglite or a baseball bat could have delivered the injuries to JonBenet's skull.
Also another feature of interest is height, in general, when a child falls down and is injured, it is the height they fall from that is important, not discounting whether they land on their arm or back, or head etc.
So the vast majority of domestic accidents presented as AE, involving children, present a range of injuries limited by the domestic circumstances.
JonBenet's head injury is classified as
serious e.g. life threatening, she had a linear fracture, various non-linear fractures, subarachnoid, and subdural bleeding, linear contusions on her right hemisphere, and small contusions on the tips of her temporal lobes, as if she had been violently shaken?
Put simply the severity and variety of JonBenet's head injuries rule out a domestic accident as the cause. Someone deliberately inflicted those head injuries, more than likely because they wanted Jonbenet dead!
