223 has more, I think.

Quoted: Energy transfer is bunk. All that matters is destroyed and damaged tissue, however it was damaged or destroyed. A boxers punch will not put a hole in the skull, pressurize the brain tissue and force it out of every orifice in the head. Thats why this question is stupid.

My thoughts exactly.

To add to this, a bullet is much smaller than a fist.  Try wearing brass knuckles...with a welded stud/point in the center.  NOW the impact (or w/e) is on one tiny spot, and will probobly inflict more pain/damage than if you used your bare fist.    

Comparing a punch of a fist to a bullet is really pointless.  If you get shot in the face, you will most likely DIE.  If you get punched in the face you might be knocked out.  The bullet is different in that it will rip through soft tissue inside your head, and then probobly leave a nasty exit wound.  

There's no use trying to figure out which has more power.  One will kill, the other most likely won't.  Why is there ANY reason to take it further than that?  
 

Quoted: Quoted: Quoted: When you guys are referring to a recoiling weapon, remember that it is momentum that is conserved rather than energy. See my post from the archives here for a full explanation including the math. I disagree. Conservation of both momentum and energy are a given. Force is another matter. If KE were conserved when you fired a high-power rifle, you would not be firing another shot. This isn't an opinion to which you can disagree, bro, it's a fact.  I'll bet my BSME on it. Did you read my archived post?  It's all in there. here's a web page explaining it further.

Your link is a dead one.

I didn't actually say that KE is what is conserved but E, though I would expect most of that conserved as KE. With a man holding the firearm that KE is dissipated in various ways.
Put that gun in space and fire it and it would be another story, IMO.

However, I appreciate that you have a BSME and am certainly open to reconsidering. I was unimpressed with your first link. Perhaps you could do a better job of explaining.

In any event, try this question if you would: Which would hit with more energy, the fist or the bullet?


My son just finished his first semester in ME. Brought him home last night.

Quoted: Easy to answer: Just take the stock of your AR, hold it to a selected part of your face.  Pull trigger. The answer is no.   Remember Newton?  Every action has an equal and opposite reaction. The drill sgt at Ft Knox put the stock to his nads and ripped off a burst.  The intent was to show that there is no recoil.

You are wrong there bud.

The kinetic energy in the velocity of the bullet and in the recoil velocity of the rifle is not equal.    

You are correct only in the respect that the force exerted on the base of the bullet and the breechface of the rifle is equal for the few milliseconds that the bullet is flying down the barrel.

"Friends don't let friends say incorrect shit about kinematics"

Quoted: Quoted: Force = Mass x Velocity. Incorrect. Force = mass * acceleration. Momentum = mass * velocity.

I think this guy took physics at truck driver school.

It is like comparing apples and oranges.  If you shoot a watermelon sitting on a stump with a .556 from 25 yards it will explode. We've all seen that.  It Bill Goldberg smacked the shit out of it his fist would probably go through the melon and/or knock it off the stump.

Now if you were standing against a concrete wall with the back of your head pressed against the wall the .556 damage wouldn't be much, if any, different than if your head were sitting on a stump.  This due to the relative vast difference in weight between the two objects and the high velocity of the bullet.

Now imagine your head pressed against that concrete wall and Goldberg hitting you as hard as he can in the face.  Since your head in the other example could move with the punch and thus dissipate some of the energy you might survive the punch.  You would NOT survive the punch it your head were pressed against something like a concrete wall.  He would crush your face/nose etc. into your brain.

So, either way you're dead.  One way develops energy via speed the other via mass and speed which creates momentum.  I could be wrong so feel free to correct me if you disagree.

Quoted: Quoted: Quoted: Quoted: When you guys are referring to a recoiling weapon, remember that it is momentum that is conserved rather than energy. See my post from the archives here for a full explanation including the math. I disagree. Conservation of both momentum and energy are a given. Force is another matter. If KE were conserved when you fired a high-power rifle, you would not be firing another shot. This isn't an opinion to which you can disagree, bro, it's a fact.  I'll bet my BSME on it. Did you read my archived post?  It's all in there. here's a web page explaining it further. Your link is a dead one. I didn't actually say that KE is what is conserved but E, though I would expect most of that conserved as KE. With a man holding the firearm that KE is dissipated in various ways. Put that gun in space and fire it and it would be another story, IMO. However, I appreciate that you have a BSME and am certainly open to reconsidering. I was unimpressed with your first link. Perhaps you could do a better job of explaining. In any event, try this question if you would: Which would hit with more energy, the fist or the bullet? My son just finished his first semester in ME. Brought him home last night.

Don't know why that second link was dead.  Try this: www.bsharp.org/physics/stuff/recoil.html
(copy and paste into your addy bar, if necessary)

The chemical potential energy of the propellant is transformed into:
1) Mechanical potential energy (high pressure gas)
2) Thermal energy (heat)

The high pressure gas (part 1 from above) expands, pushing both the bullet and the gas itself down the bore, and converting all of its mechanical potential energy (again, part 1 above) into kinetic energy.  If the above link were working, you would see that the bullet's KE is significantly greater than that of the gas.  That means any KE calulations can exclude it while remaining accurate enough for our purposes.

The heat (part 2 from above) is simply wasted energy.  If we found a way to sufficiently and practically insulate the chamber and barrel this heat could be retained by the gas, contributing to greater pressure and therefore greater bullet KE.

Perhaps you're point was that the total energy released from the combustion of the propellant must be accounted for?  I agree.  It's in the form of parts 1 and 2 above.

The misconception that my recoil energy thread was meant to address is that the kinetic energy of the bullet and the rifle are equal.  Not so.


ETA:  Tell your son to hang in there.  It gets much more interesting junior year.

Quoted: It all depends on the "power factor" and "energy dump"

I took an "Energy Dump" at about 9:30 am this morning.

Quoted: Let me punch you in the face and then I will shoot you in the face point blank then you can decide for yourself.

I was thinking the same.

Quoted: Quoted: Energy transfer is bunk. All that matters is destroyed and damaged tissue, however it was damaged or destroyed. A boxers punch will not put a hole in the skull, pressurize the brain tissue and force it out of every orifice in the head. Thats why this question is stupid. My thoughts exactly. To add to this, a bullet is much smaller than a fist.  Try wearing brass knuckles...with a welded stud/point in the center.  NOW the impact (or w/e) is on one tiny spot, and will probobly inflict more pain/damage than if you used your bare fist.     Comparing a punch of a fist to a bullet is really pointless.  If you get shot in the face, you will most likely DIE.  If you get punched in the face you might be knocked out.  The bullet is different in that it will rip through soft tissue inside your head, and then probobly leave a nasty exit wound.   There's no use trying to figure out which has more power.  One will kill, the other most likely won't.  Why is there ANY reason to take it further than that?

Quoted: Quoted: Quoted: Easy to answer: Just take the stock of your AR, hold it to a selected part of your face.  Pull trigger. The answer is no.   Remember Newton?  Every action has an equal and opposite reaction. The drill sgt at Ft Knox put the stock to his nads and ripped off a burst.  The intent was to show that there is no recoil.   uh ,no.  Because the mass of the gun is much greater than the mass of the bullet being fired out of it. Right, but it has the same energy imparted to it.  It just weighs 900-1000 times more than the bullet it's sending down.  So it accelerates much more slowly rearward than the bullet does forward. Same with your fist.  You wouldn't have to accellerate it nearly as fast to develop the same energy because the mass part of the formula is several hundred times higher.

I detect a bit of a misunderstanding.  In actuality the momentum (mV) of the rifle and the ejecta (bullet plus propellant) would sum to zero.  There is no requirement whatsoever for the kinetic energy (mV^2) of the rifle to be equivalent to that of the bullet.

Power on the other hand is work done per unit time.  If you compare the power of the bullet and a punch only over the duration of their interaction with their targets, my money is on the bullet being more "powerful" because of the extremely short duration of the interaction.

Didn't they do something like this on mythbusters? They were very unimpressed by the amount of energy imparted to a maniquin wearing body armor. 12ga. buckshot ,.223 even .308 would barely move the torso, way less movment than a punch would.

Pull your heads out of the textbooks for a minute and think it thru.

Quoted: Quoted: yea but can chuck norris stop mighty mouse That mouse would get lost in his beard

What about this mouse?: