How does a bullet or knife kill somebody?

How does a bullet or knife kill somebody?

So, there are bullets that can actually transform human flesh into ground beef? How do they work, Cece?


I thought there was some doubt about the whole hydrostatic shock thing.

I saw that “literally” phrase and wondered, but made me scratch my head more was the fact that he mentions Tom Clancy…in 1979! I thought Hunt For Red October came out in 1984? Was Tom Clancy even known in 1979?

that should say, “but what made me scratch my head.” oops. Oh, why can’t I edit my previous post???


Additionally, I may be wrong (because I’ve never actually shot anyone with my hollowpoints) but I was under the impression that they have to hit something hard, like bone, in order to deform? Cecil makes it sound as if it flattens when it hits skin…

Indeed. This was discussed a couple of months ago in this thread, (in which I brought up hydrostatic shock as the primary gunshot damage mechanism):

Gun Shot Survival Rate

So I got the idea of “hydrostatic shock” from none other than Cecil, huh?! :dubious:

Hmm. Kinda sorta answered my own question about hollow points, according to the book Understanding Firearm Ballistics by Robert A. Rinker, the hollowpoint expands upon “impact” and tears through the flesh. Of course impact is not defined as with flesh or with bone :wink:

The same book has some good info on hydrostatic shock and effects of bullets on bodies… if anyone is interested in a scientific read, but in terms that anyone can understand, and need more info than the title and author let me know.

I though the whole thing had been completely debunked. To give Cecil credit, though, he was writing that in 1979. Omniscience has its limitations.

Role-playing gamers certainly seem to think it’s a myth, anyway:


Ah, thank you for the informative links.

The bullet may expand when it travels through tissue due to the increased density of the tissue over air. I say “may” as it depends upon the hollowpoint design, and whether or not the tip is plugged or damaged from striking something before entry.


To address the question in the OP, it depends on whether “hamburger” is necessarily beef. I’ve seen patties made from turkey meat described as “hamburger”, for instance, and what’s left after the bullet goes through a human body is, indeed, ground meat.

What does he mean by geometrically? It makes geometric shapes?

I think it means that if you double the mass, you double the Kinetic Energy, but if you double the velocity, the KE goes up by 2 squared.

Webster says “ground beef [or] a patty of ground beef,” but says "Ground meat, usually beef. [or] A patty of such meat.

You may be right; that may be what Cecil meant. I had always thought “hamburger” referred exclusively to beef, but apparently it doesn’t always.

Put simply, both knives and bullets poke a hole in a person and they bleed to death. Depending on where the hole is and how big, there may be other effects- i.e., if the person gets shot or stabbed in the central nervous system, they may be paralyzed, die instantly, etc…

Now inside bullets there are basically two types- high velocity rifle bullets and low velocity handgun bullets.

All high velocity bullets will eventually tumble on contact with flesh, water, gelatin, etc… When that happens, the bullet tears up a greater area than the diameter of the bullet. The main reason that the smaller and lighter rifle calibers have a reputation for lethality is because they are lighter, and therefore tend to yaw very quickly (~5-10 cm) when compared to larger calibers such as 7.62mm(~15-20 cm). This means that larger bullets frequently pass straight through people before they begin to tumble, while the smaller bullets tumble very quickly and do a great deal of damage. The M16 bullets have one more added effect- they tend to come apart when they begin to tumble, creating a MUCH larger wound.

Low velocity handgun bullets are traveling slowly enough to where they do not tumble on deceleration. Therefore, they tend to make a wound roughly the diameter of the bullet. Hollowpoint rounds are intended to expand the front of the bullet in order to make a larger diameter wound- a typical 9mm round expands to 19mm and penetrates about 23 cm. As handgun bullets get larger, so do the holes they make, accounting for the popularity of the .45 ACP cartridge.

Here are my cites:

Here’s another interesting link:

Except that that’s not what the term “increases geometrically” actually means.

As you said, KE is proportional to v[sup]2[/sup]. This would be described as saying that kinetic energy increases quadratically with velocity. (“quadratic” because it increases as the square of the velocity, and a square has 4 sides – “quad”, get it?)

If knetic energy really did increase geometrically with velocity, it wouldn’t be proportional to v[sup]2[/sup], it would be proportional to 2[sup]v[/sup]. This would mean that every +1 foot-per-second (meter-per-second, etc.) increase in velocity yields double the kinetic energy. Obviously, that isn’t the case.

I thought that was called an exponential increase.

Man, one of these days I’m gonna send a question to Cecil about “chronic sleep debt.”

– Jay

Bullets and knives don’t kill people. (They lack a motive, the will, and the physical ability to carry it out.) I have had over one hundred of each in my home for years, and I’m still kicking…Get back in your box, Hollowpoint–no one’s addressing you. Why don’t you and the Cleaver go outside and play mumblety-peg with Mack?

Big animals that are angry or hungry (there’s that ending again >:^D), bacterial and viral infections, allergic reactions, people, high falls, and watching Who Wants to Marry an American Idol Millionaire who’s a Survivor in the Real World of Jerry Springer will do the trick.

Exponential growth and geometric growth mean the same thing. So Cec was wrong about “geometrically”