Can anyone show me a 45 mm handgun

[JohnKSa]

In your “first equation,” Favg = .5 m v^2 / d, recognize the m and v are NOT the mass and velocity of the bullet, they are the mass and resulting velocity of the affected mass.

I have no idea how you came to that conclusion. It is certainly not consistent with any of the information in the provided links or formulas.

In the second equation, Favg = m v / t, we DO have a simple means to know the mass and velocity terms. Momentum is conserved, such if we know if the bullet stops in the target, or we can determine the velocity of the bullet upon exit, then we know the momentum transferred to the target.

You have the same simple means to know the mass and velocity of the projectile in either case. Measure them as you would the velocity and mass of any projectile.

Neither equation has to do with "momentum transfer" or "energy transfer" or conservation of either momentum or energy. They are both equations for the force applied by an impact. One calculated from energy and the distance of the impact and the other from momentum and the time of the impact.

The explanation provided in the link associated with the two formulas explains things quite clearly. There's absolutely nothing in the link that suggests the formulas are about momentum transfer or energy transfer--the word "transfer" doesn't even appear on that web page. As for the "affected mass", basic physics indicates that the force applied to the target is equal to the force applied to the projectile so it's the same force either way.

Your comments about momentum transfer and conservation of momentum are accurate--they just have nothing to do with the formulas/links or my comments. My comments and the links and formulas are not about any kind of "transfer", they are about the force generated by an impact (i.e. how changes in energy/momentum relate to force applied and vice versa) and the ways it can be calculated.

Bottom line is that projectile impact force** can be calculated from either projectile energy and the distance required to stop the projectile or projectile momentum and the time required to stop the projectile. The formulas are clear, the information in the link is clear, my explanations are clear and they all agree and if, for some reason, you don't like any of those, you can easily find other sources that will tell you the same thing.

**Please note that "projectile impact force" is not the same as "momentum transfer" or "conservation of momentum" or "conservation of energy".

 

[Varminterror]

A baseball bat swinging has far more Energy available than that which is given to the baseball.

The energy on the bullet is only the amount of Energy which can be done as work - recognizing losses of kinetic energy to other forms of energy. What energy is on the bullet has no bearing on how much energy results as energy to the target, none beyond a maxima.

Read and understand the math I provided which outlines the inelastic collision formulas in my last message. You’d be a lot closer than you are right now.

A yielding target does not accept all of the available kinetic energy from the bullet as kinetic energy on the target - hence, inelastic collisions...

 

[JohnKSa]

A baseball bat swinging has far more Energy available than that which is given to the baseball.

Sure. But I wasn't talking about conservation of energy, I (and the links and formulas I provided) are about impact force.

Impact force is not energy, although it can be calculated from it. Impact force is not momentum either, although it can be calculated from it, too. Your comments about energy conservation and momentum conservation are accurate--the disconnect is that those comments are not about the same thing I'm talking about which is the calculation of impact force.

The energy on the bullet is only the amount of Energy which can be done as work - recognizing losses of kinetic energy to other forms of energy. What energy is on the bullet has no bearing on how much energy results as energy to the target, none beyond a maxima.

All correct. But, again, you're still talking about something different from what I am and from what is discussed in the links and calculated by the formulas I provided.

Read and understand the math I provided which outlines the inelastic collision formulas in my last message. You’d be a lot closer than you are right now.

A yielding target does not accept all of the available kinetic energy from the bullet as kinetic energy on the target - hence, inelastic collisions...

I have read them, I do understand them, and you are not wrong, nor are they. The problem is that you are focused on something other than impact force calculation which is what I'm talking about.

Perhaps the issue is that although my initial entry into this thread was in response to comments by Spats regarding the force applied to the target, I quoted your response to his question and your response was about momentum, not about force applied to the target. Your post that I quoted was correct in terms of the physics and math but I quoted it and responded to it because it did not answer the question about impact force, rather it talked about momentum calculation.

If that's where the misunderstanding arose, I apologize for the misdirection.

From the beginning, I have been talking about impact force calculation in response to the earlier question on the thread. I have not been talking about conservation of momentum or conservation of energy, or energy transfer, or momentum transfer. You appear to have a correct understanding of energy/momentum conservation/transfer; but those things are just not the same thing as impact force.

 

[MTMilitiaman]

The image of David twirling a leather strap over his head is probably inaccurate. David was a Shepard, and probably used a "Shepard's Sling." The Shepard Sling was typically placed on the end of their staff/walking stick. This provided additional leverage and is similar in concept to using an atlatl to throw a spear.

 

[swede4198]

It's not 45mm but a cousin of mine used one of these as a helicopter pilot in Viet Nam when he was shot down a couple of times. With the buckshot rounds he said it was guaranteed to suppress enemy fire while he and the crew ran the other way.