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Thread: Physics Question ??

  1. #1
    Senior Member kyratshooter's Avatar
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    Default Physics Question ??

    I have been searching for the answer to this question for two days and can get nowhere. Seems you can find any information you desire on the internet unless it deals with math or physics.

    At one time I knew this stuff, but it has been 45 years since I sat in a physics classroom.

    If two identical projectiles traveling at the same velocity strike a point at the same instant is the energy of their impact multiplied or squared?
    Last edited by kyratshooter; 10-15-2015 at 11:48 PM.
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  2. #2

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    Are you are trying to describe Kinetic energy?

    kinetic energy (E) of a massive body in motion can be calculated as half its mass (m) times the square of its velocity (v): E = ½mv2. Note that energy is a scalar quantity, i.e., it does not depend on direction, and it is always positive. When we double the mass, we double the energy; however, when we double the velocity, energy increases by a factor of four.

    from

    http://www.livescience.com/46278-kinetic-energy.html
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    Administrator Rick's Avatar
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    I think, technically, the answer is: Increased.

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    Senior Member Old GI's Avatar
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    Physics are good if used sparingly. I maintain pretty good regularity ....... oh, nevermind.
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  5. #5

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    If two identical projectiles traveling at the same velocity strike a point at the same instant is the energy of their impact multiplied or squared?
    Since they are separate and really cannot strike the exact same point at the exact same time, it is a hypothetical. But, if you did make them combine and strike the same point at the same time. And since their velocity is the same, you have only doubled the mass.

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    Resident Wildman Wildthang's Avatar
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    Multiplied X2

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    Senior Member hunter63's Avatar
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    OMG....Just had a FLASHBACK...I was told that there would be no maff........(60's were a be-atch)....

    Y'all let me know what you decide........
    Need to go out a rake some leaves.....
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    If 2 cars hit head on at 50 mph, they both experience the same energy as hitting a brick wall at 50 mph, if that helps.

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    Senior Member hunter63's Avatar
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    So I said into the phone.....

    "Siri....If two identical projectiles traveling at the same velocity strike a point at the same instant is the energy of their impact multiplied or squared?"

    Siri said, "How the heck would I know?...you think I'm a computer or something?"

    (snort, giggle....Sorry couldn't resist....)
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    Senior Member kyratshooter's Avatar
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    Hey, there is a practical side I'm dealing with...

    Trying to work up the energy transferred by a buckshot load based on how many of what sized pellets strike the target.

    It is the continuation of an open choke vs. tight choke discussion on a tacticool shotgun forum.

    Yes I occasionally stray from the flock.
    Last edited by kyratshooter; 10-16-2015 at 02:00 PM.
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    Administrator Rick's Avatar
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    Oh, well, heck. If it's for a forum any answer will do. Lemme think about it....doubled.

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    Senior Member kyratshooter's Avatar
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    Yep, after this discussion I am pretty much convinced that I can put down any numbers I want and no one will say anything for fear of having to do square route to prove me wrong!

    I am closing in on realizing that the impacts are multiplied rather than squared. If they were squared/cubed/quadrupled... the impact of 5-6 buckshot would propel the target into low earth orbit.

    I already brought down one space shuttle shooting a lodged ramrod out of a CVA Blazer rifle, I don't need another incident.
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  13. #13

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    If two cars hit head on doing the same speed, the force is doubled. Not a brick wall. Trick physics question. Do the math.
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    Super Moderator crashdive123's Avatar
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    Krat - just tell them the force is multiplied by a factor of 3.87 and act like you mean it. Before long you will be reading all over the internet.
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    Senior Member hunter63's Avatar
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    Quote Originally Posted by crashdive123 View Post
    Krat - just tell them the force is multiplied by a factor of 3.87 and act like you mean it. Before long you will be reading all over the internet.
    ...........from this day forward......Bhohahaha
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    Senior Member natertot's Avatar
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    Kyrat, in the instance of your initial post, the energy is simply doubled. If it were three projectiles, it would be tripled. Four would be quadrupled and so on. This is strictly on the projectile side of things. The force of impact is not as linear as the energy however. Think about a shotshell containing 1 oz of #8 vs a 1 oz slug. Both contain the same about of weight of the same metal, but the force of the slug is much greater because it is concentrated. Same thing with your OP. More projectiles will cause greater damage, but fewer projectiles with more mass will cause even greater damage yet.

    Sorry, there is no clear cut answer as there are too many variables and I am not certain what the exact specifics are.
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    Senior Member kyratshooter's Avatar
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    It was just one of the age old discussions about the craze for cylinder bore home defense shotguns.

    The old thing where those that have never fired a shotgun think that they are going to hit/kill five people with one pellet each and the ones that have fired a shotgun and know that you want all the buckshot to hit one target will all the force available.

    Just the normal forum stuff. But I wanted to give them the razzle dazzle with the math and shut them up, or at least scare them with long division and powers of 10.

    Working up the numbers it takes two pellets of #00 buckshot to equal one 125gn 9mm/38spl impact, so unless you hit a vital organ or penetrate to the central nervous system with one of those pellets you better hope you get lots of them on target, because individually they do not have much in the way of stopping power.

    There is a theory of multiple impact trauma that claims that when you are hit by numerous projectiles at the same instant the reaction of the body is different than if they are spread out over a time frame. It is one of the philosophies behind the use of the "double tap" in combat handgun training. There was a lot written about it back in the ancient days of the 1970s, but I can find none of the articles now.
    Last edited by kyratshooter; 10-17-2015 at 03:09 AM.
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    Senior Member 2dumb2kwit's Avatar
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    Home defense? If you are trying to figure out what choke to use to stop a home invader.........how big are your rooms? Hahahaha.

    (Y'all must have a much bigger house, than I have.) LOL
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    Quote Originally Posted by natertot
    Kyrat, in the instance of your initial post, the energy is simply doubled.


    See that? Post 11. And you ya'll thought I was just another pretty face.

  20. #20
    Senior Member kyratshooter's Avatar
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    Quote Originally Posted by 2dumb2kwit View Post
    Home defense? If you are trying to figure out what choke to use to stop a home invader.........how big are your rooms? Hahahaha.

    (Y'all must have a much bigger house, than I have.) LOL
    The house is not big, but down the hall, bedroom to back door, I have 60 feet/20 yards.

    I have also been known to take the shotgun outside when something is in the chicken house or a known coyote type varmint is lurking about. I have 37 yards to the back fence and about 30 yards to each side of the yard.

    Either of those situations needs some choke to keep things all in the same general area and effective.

    While the "riot gun" with 18" barrel can be effective at the extreme close ranges of the indoor arena, not having a choke restricts the weapon to only extreme short range use and makes it useless for what the industry has worked so hard for the past 150 years to develop.

    It has also created a widespread myth that the shotgun is no good for anything past 20 yards and useless for anything but indoor home defense. While that might be true for THEIR shotguns, it is not true for mine, or anyone else that has a modified or full choke or choke tube in their pea shooter.
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