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  1. #31
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    Sometimes momentum (MV) beats kenetic energy (1/2 MV^2)

  2. #32
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    Quote Originally Posted by 45Smashemflat View Post
    Sometimes momentum (MV) beats kenetic energy (1/2 MV^2)
    Momentum and kinetic energy are two different ways of quantifying the kinetics of the same system. One doesn't "beat" the other.

  3. #33
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    Quote Originally Posted by 45Smashemflat View Post
    As I tell folks, "everything that has been hit with it seems appropriately impressed." I've used a 45/70 for years, and I renamed it what you see as my user name.

    Buddy of mine, who had some disability in terms of still hunting, turned me on to it as a serious one shot stop machine. He dropped more animals shooting them in the poop chute with his 45/70 than I can count. He called it the Portugese head shot... Generally he could count on full penetration LENGTHWISE through white and black tail deer, hogs, and moose.

    And yes, I see the humor. Like shooting dueling trees with one shooter on a 9mm and the other on a 45ACP. Ping, swwwwinnng. BANG, swing, SMACK!
    My uncle waited until one hogs head lined up with another hogs spine and got a 2-for-1 with it once. Blew a golfball sized hole in the ones back and crushed the skull of the other to an unrecognizable level. Pretty destructive when used properly.
    "We are what we repeatedly do. Excellence, therefore, is not an act, but a habit." -Aristotle

  4. #34
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    Jun 2012
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    Kinetic Energy is how much "work" the projectile can do. Momentum is how much kinetic energy the projectile will retain once external forces start acting on it.

  5. #35
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    Below are text book explanations of momentum and energy.
    In the world of warfare and hunting smaller, faster projectiles have replacing larger slower ones over the centuries. The problem is the lighter projectiles shed their energy quicker and in some applications they will kill less effectively because of it.
    In Newtonian mechanics, linear momentum, translational momentum, or simply momentum (pl. momenta) is the product of the mass and velocity of an object. It is a three-dimensional vector quantity, possessing a magnitude and a direction. If m is an object's mass and v is the velocity (also a vector), then the momentum is
    p = m v , {\displaystyle \mathbf {p} =m\mathbf {v} ,}
    In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes.
    What is the relationship between kinetic energy and momentum?

    Relation between momentum and kinetic energy. Note that if a massive particle and a light particle have the same momentum, the light one will have a lot more kinetic energy. If a light particle and a heavy one have the same velocity, the heavy one has more kinetic energy.
    One who hammers his gun into a plow plows for those who do not....Unknown
    ...at the end of the day its not about anything else but YOU AND YOURS..... Gabe Suarez
    ....WANT not NEED is what America is all about. ..... Gabe Suarez
    Its not about how fast you can load, but about how well you can shoot ..... Someone being saved by a speed load is not something that has happened with any regularity. Gabe Suarez

  6. #36
    Quote Originally Posted by barnetmill View Post
    Below are text book explanations of momentum and energy.
    In the world of warfare and hunting smaller, faster projectiles have replacing larger slower ones over the centuries. The problem is the lighter projectiles shed their energy quicker and in some applications they will kill less effectively because of it.
    You either spend alot of time on your computer. Or you have Wikipedia on speed dial.

    Regarding the topic of the discussion. If I have a 300 Blk. I'm going to use it. If I have a 45-70, I'm going to use it.
    A man can be right all the time. In which case he can do so, all by himself.

  7. #37
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    Quote Originally Posted by BeardedPelican View Post
    You either spend alot of time on your computer. Or you have Wikipedia on speed dial.

    Regarding the topic of the discussion. If I have a 300 Blk. I'm going to use it. If I have a 45-70, I'm going to use it.
    The last sentence is a good statement. Either in the hands of a competent hunter will bring in the bacon. For self defense against large north american mammals I would likely not choose either. I think there are better choices out there. But with the right bullets and skill either can be used for self-defense against large critters.
    You may not like how I answered defining what momentum and kinetic energy are, but these explanations are correct and might serve as a foundation to a better discussion of this topic. One reason I am here and stay here is that the SI people come up with equipment and tactics that cut through the BS that people put out to show the best way to win a fight. Be nice if people could apply such knowledge to other gun related issues.

    Speeding up the 45-70 is an old idea and there were 45-90 express loads as I recall and these were sold until the middle of the great depression and when WWII ended the production of these were not resumed. I wonder why? Today there are muzzle breaks, better steel, and modern smokeless powders to improve upon the old black powder idea of express loads.
    One who hammers his gun into a plow plows for those who do not....Unknown
    ...at the end of the day its not about anything else but YOU AND YOURS..... Gabe Suarez
    ....WANT not NEED is what America is all about. ..... Gabe Suarez
    Its not about how fast you can load, but about how well you can shoot ..... Someone being saved by a speed load is not something that has happened with any regularity. Gabe Suarez

  8. #38
    Join Date
    Jan 2014
    Posts
    785
    Sorry, but I'm a physicist...

    Momentum is momentum, and kenetic energy is kenetic energy. Both are conserved. How much a certain bullet leaves in the "animal" struck is a function of shot placement and bullet construction.

    The reaction of said animal to the resulting "dump" of momentum and energy into its body is a function of the animal, and again, shot placement.

    Big fat bullets are working to leverage the conservation of momentum equation. Fast bullets are working to leverage the kenetic energy equation. Note, KE is a function of the SQUARE of speed, so tiny increase in velocity equal large gains in KE.

    BUT, if the bullet punches through and exits retaining speed, it has "left" very little KE in the animal. Which means you didn't kill it fast.

    Just some nerd stuff to contemplate...

  9. #39
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    Quote Originally Posted by 45Smashemflat View Post
    Sorry, but I'm a physicist...

    Momentum is momentum, and kenetic energy is kenetic energy. Both are conserved. How much a certain bullet leaves in the "animal" struck is a function of shot placement and bullet construction.

    The reaction of said animal to the resulting "dump" of momentum and energy into its body is a function of the animal, and again, shot placement.

    Big fat bullets are working to leverage the conservation of momentum equation. Fast bullets are working to leverage the kenetic energy equation. Note, KE is a function of the SQUARE of speed, so tiny increase in velocity equal large gains in KE.

    BUT, if the bullet punches through and exits retaining speed, it has "left" very little KE in the animal. Which means you didn't kill it fast.

    Just some nerd stuff to contemplate...
    There a lot to be discussed in the above. I am a biologist and not a physicist. It really depends on what in the body gets smashed as to what causes the fastest death or incapacitation. Marksmanship, bullet construction, and enough momentum and energy to penetrate, shock, and break/destroy the most important vital structures is what counts. The shock aspect needs more discussion and I do not understand this component of wounds ballistics very well.
    One who hammers his gun into a plow plows for those who do not....Unknown
    ...at the end of the day its not about anything else but YOU AND YOURS..... Gabe Suarez
    ....WANT not NEED is what America is all about. ..... Gabe Suarez
    Its not about how fast you can load, but about how well you can shoot ..... Someone being saved by a speed load is not something that has happened with any regularity. Gabe Suarez

  10. #40
    Join Date
    Sep 2009
    Posts
    7,446

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