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Target Fragment Speed

Discussion in 'Shooting Related Threads' started by Jim Porter, Aug 18, 2010.

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  1. Jim Porter

    Jim Porter Well-Known Member

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    I am not an educated man and I have wondered about this for many years. Although I must admit it really dosen't matter and I have pondered on a few other things from time to time. I would like to know what the scientific answer is though.

    When a shot string breaks a target and fragments fly away, they seem to increase speed. Is is an illusion? If not why do pieces gain speed? Is it a result of rotational force? Is it added energy from the shot strike? Is it energy that is relayed from a larger item to a smaller piece? What is really going on???

    After this somebody tell me. If a thurmos bottle can keep hot stuff hot and cold stuff cold, HOW DOES IT KNOW????
     
  2. mixer

    mixer Well-Known Member

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    The thermos bottle knows because the cap tells it what to do. I thought everyone knew that.

    Eric
     
  3. TEXASZEPHYR

    TEXASZEPHYR Member

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    as for ur thermos, it doesn't keep it hot or cold, It just keeps it close to the original temp and is affected by it's enviornment.

    The target fragment, I'd bet is a product of the wt-speed of object being hit and the wt/speed (applied energy) of the object doing the hitting. Neil W could probably give you the exact formula to come up with a more concise answer

    Bob
     
  4. Neil Winston

    Neil Winston Well-Known Member

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    Eric is close, but that's not quite it. The silver coating is heat impermeable and so neither heat nor cold (in spite of their being very different things) can pass through. Imagine the attitudes of so many here - it's the same kind of thing.*

    Neil

    * Please, please, don't believe the part about the thermos bottle. Think instead about

    1. What happens when you hold a mirror up the the sun and shine the reflection of that star on your face and

    2. Consider what the back-side of a mirror looks like.
     
  5. Neil Winston

    Neil Winston Well-Known Member

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    More seriously, I'm afraid I have to disagree a bit with my friend TZ. The speed of the target shards flying away is an example of Newton's First Law which says that things keep on at a constant velocity (which is often zero) unless acted upon by an outside force.

    Consider a spinning target, which if friction were perfect on the arm would have a speed-of-rotation near 3000 RPM. The bits at the edge are moving very fast, those nearer the center less fast, and at the very center, only as fast as the target itself, which is 30 to 33 MPH.

    As the target shatters, the bits continue on at their pre-shattering velocity, so some go very fast, others less so, and some of the big pieces just seem to do pretty-much what the whole target was doing before anything happened to it.

    And no, it hardly seems possible that the pellets themselves have much influence in any of this at all, other than disrupting the integrity of the target.

    But you have to be careful here. When you consider every bit, the total momentum of the entire system will stay close to the same, that is, it will all add up to the same mass x velocity (target x target speed) before and after being hit.

    This is, as you see, a big problem for theorists who think you "read the breaks." If I'm right, you can't.

    Neil
     
  6. TEXASZEPHYR

    TEXASZEPHYR Member

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    Neil, I know that I have hit some of the aluminum type targets with a good centered hit and have seen them fly off in a direction different than that to which they were launched. With this being the case, I would suggest that a good center hit with 7 or 8 nr 7 1/2 pellets would likely have some affect on the course of flight on a target. Like you said surely the math on this could be figured, however with a shattered target if would be near impossible to determine which piece of the shattered target was affected by which piece of shot, and thusly making the whole process somewhat futile. Using the aluminum target example might give some hope if we knew the weight of the target
    Respectfully,

    Bob w
     
  7. Trap2

    Trap2 Well-Known Member

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    Jim..... I don't know about the thermos bottle, but, I too have a couple questions that beg for answers:

    1) If an airplanes black box is made out of indestructable material, why don't they make the whole damn plane out of the same material????

    2) If 7-11's are open 24 hours a day, 365 days a year, why do they put locks on the doors??????

    Inquiring minds want to know....

    Dan Thome (Trap2)
     
  8. Neil Winston

    Neil Winston Well-Known Member

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    Bob, thanks for the reply; I hope my editing of my previous post - before I read yours - does not seem like dirty pool.

    Let's agree that a target has a weight of 100 grams and a pellet weighs (one fourth of that is one ounce) times one four-hundredth, the number of 7 1/2's in an ounce, or about 1/1600th as much as a target. Let's also agree that the pellet is going twenty-times as fast as the target. That means that the maximum possible influence of a single pellet on the momentum of a target is 20x1/1600 or 1/80.

    That would be true if all the momentum of the pellet were transferred to the target and you were looking from above, where you could see what happened when the pellet hit the target straight on. Its speed would be increased by one in eighty which I think would be hard to see, it being a change from 30 to 30.3 MPH.

    A hit by a pellet from more angle than dead center will of course have less effect, the momentum being changed (I think) by a magnitude of the earlier effect times the cosine of angle off of dead center that the impact occurs.

    There are two reasons for this:

    1. The force of blow is reduced by the relationship I stated above (again, I think) and

    2. I seems to me that a glancing blow will transfer less momentum, that is, the more angular the hit, the faster will be the velocity of pellet as it bounces off and does not break the target and so the less will be available to "move" the target.

    I am open to argument on all of this, but the ribs in my analogue Brinkman (I don't have a Prevost; I don't have a digital smoker) are calling me.

    Neil
     
  9. ivanhoe

    ivanhoe Well-Known Member

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    There are many interesting questions out their like these.

    How is it that we put man on the moon before we figured out it would be a good idea to put wheels on luggage????

    How important does a person have to be before they are considered assassinated
    instead of just murdered?????

    Why are you IN a movie, but you're ON TV?????

    Bob Lawless
     
  10. phirel

    phirel TS Member

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    Bob- When you hit a aluminum type target much, perhaps all of the energy in the shot is transfered to the metal. When you hit a clay target with shot, only a little of the shot energy is transfered to the target as the shot passes through the target and then travels on with its remaining energy.

    A target piece would move with the energy moving the target forward at 30-35 MPH plus the energy that is spinning the target around 3,000 RPM. For a short distance, this should make the pieces appear move faster than the target. But they actually do not because the total movement of the target is forward (we can see this) and it also has rotational movement. The true speed of the target is the sum of the forward and rotational movement.

    This thread has the flavor of something Neil, ZZT and I could form into an esoteric discussion. I like that.

    Pat Ireland
     
  11. Neil Winston

    Neil Winston Well-Known Member

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    Pat, one possible characteristic of things that appear to move faster is that they are moving faster. Like target pieces, which are, indeed, moving faster.

    Please click on the above link; I so seldom have a chance to pounce on you from two sides.

    Besides, I darn near fell asleep in the BOD meeting. I never did that when you and TK and the other Pat and I were there! Nor did, as I recall, many others!

    Neil
     
  12. BudsterXT

    BudsterXT Member

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    Ummm, I am just happy when they break.
     
  13. phirel

    phirel TS Member

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    Neil- I was considering the movement of the whole target as the sum of its linear speed and its rotational speed. When a target breaks, the linear speed remains constant but the rotational speed is converted into linear speed. This would increase the linear speed but eliminate the rotational speed. The result would be that the pieces appear to move faster because all we can see is the linear movement of the target.

    A practical demonstration. Put a sanding disk on your electric drill and then put a glob of peanut butter on the disk. Sit in your favorite living room chair and hold the drill/disk parallel with the floor. Slowly increase the speed of the drill until the glob of peanut butter flies off. The peanut butter will not move faster as it flies off. It will only move in a different direction (from rotational speed to linear speed). Next, clean up the mess you made.

    Pat Ireland
     
  14. sliverbulletexpress

    sliverbulletexpress TS Member

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    My theory is the clay bird speeds up to get out of the way when I manage to get some shot close to it. They seem to get better at it as time goes on.
     
  15. Neil Winston

    Neil Winston Well-Known Member

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    That's a great demonstration, Pat, and all I ask is to make one small modification it it.

    The drill is cordless with the sanding disk and the peanut butter and all that, You are walking slowly across your livingroom and idly press the trigger of the sander as we all do like three-year-olds.

    The peanut butter is moving because you are holding the drill and walking. That is analogous to target flight. Some of the peanut butter lands ahead of you and the only way it could have done so is that it was, in fact, moving faster than you were. So this is not some kind of weird visual illusion; we see what is actually happening and Mr. Porter has perceived it correctly. The piece has moved faster than the whole object would have been been mentally predicted to move.

    Neil
     
  16. hmb

    hmb Well-Known Member

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    When you ink ball the target, what happened to the linear and rotational speed? The inkball just sits there motionless. HMB
     
  17. zzt

    zzt Well-Known Member

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    It doesn't sit motionless HMB, it boils.

    I'll also suggest that some of you should take a much, much closer look at Welderman's high speed movies. He will send you the higher resolution version if you ask. Reviewing Dr Jones images recorded in his "reading the breaks" series can also be helpful, but Welderman's are the best.
     
  18. aabradley82

    aabradley82 TS Member

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    If the target pieces speed up in relation to a mathematical formula does the same formula explain how when you burn a bearing on a trailer and the wheel comes off it always passes you on the interstate. haha

    Andrew
     
  19. phirel

    phirel TS Member

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    Andrew- It is the same thing as a target piece. The bearing is moving forward at 70 MPH with the car and also moving in a circle at +- 15 MPH (it is near the center of the wheel). when it breaks off and all motion is directed forward, the speed will be 70 + 15 = 85 MPH in relation to the ground. In relation to your car, it will only move forward at 15 MPH.

    If you are sitting in a car traveling at 70 MPH and toss a tennis ball up, it will come straight down and you can catch it. In relation to the ground, the ball and you are moving at 70 MPH. In relation to you the ball would only be moving straight up and down. In relation to the ground, the ball would be moving forward at 70 MPH and up at whatever speed you tossed it up.

    Pat Ireland
     
  20. scooterbum

    scooterbum Active Member

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    The real bummer is when the trailer passes you up, after becoming unhooked.
     
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