Queston at pouch release distance max speed
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The laws of physics would dictate that as soon as the acceleration of the bands no longer acted on the projectile the projectile would begin to decelerate. So when it leaves the pouch it is slowing down.
frosty2
I am by no means an expert, but have thought about this some, and of course watch Joerg's videos.
What I have noticed from the videos in slow motion and what my sense is telling me is that with 'normal' slingshots that have some slack from the fork to where the user starts encountering resistance, the max speed of the shot is going to be achieved when the band (or tube) stops "pulling" the ball forward.
So say you have say 9 inches of band or tube slack before you start pulling, and you pull that out to say 36 inches. The shot will actually be being pulled and accelerated forward by the band or tube for the 27 inches that you have pulled the band back, after that, the band is just following the shot through and not exerting any more force and therefore the shot has reached its maximum speed as soon as the band or tube stops "pulling", which would be your slack length (not sure if that is the right term).
Can't wait for more answers as this is something I really want to nail down. Then maybe someday I will figure out how the whole force thing works.
Great question!
What I have noticed from the videos in slow motion and what my sense is telling me is that with 'normal' slingshots that have some slack from the fork to where the user starts encountering resistance, the max speed of the shot is going to be achieved when the band (or tube) stops "pulling" the ball forward.
So say you have say 9 inches of band or tube slack before you start pulling, and you pull that out to say 36 inches. The shot will actually be being pulled and accelerated forward by the band or tube for the 27 inches that you have pulled the band back, after that, the band is just following the shot through and not exerting any more force and therefore the shot has reached its maximum speed as soon as the band or tube stops "pulling", which would be your slack length (not sure if that is the right term).
Can't wait for more answers as this is something I really want to nail down. Then maybe someday I will figure out how the whole force thing works.
Great question!
I just wonder if there is a speed at a specific point that the projectile is neither speeding up nor slowing down. That is to say if it has reached a speed of 300 fps why would there not be a specific distance that woudl remain the same maximum speed lets just say that sweet spot lenght could be 3 or 5 feet from the projectile as it exactly seperates from the pouch.
Another way to ask this. Isnt there a moment in time where maximum velocity is reached and this velocity is held in a moment in time translating this into a specific distance?
Dosent a pitcher do this?
Another way to ask this. Isnt there a moment in time where maximum velocity is reached and this velocity is held in a moment in time translating this into a specific distance?
Dosent a pitcher do this?
The projectile responds immediately to any outside force it encounters. The moment those forces change the effect is instantaneous. The behavior of the projectile, once the force of the pouch is absent, is subject to gravity, wind resistance and inertia primarlly (we will ignore the spin of the earth). The projectile has no way to produce any energy it has only what is imparted by the slingshot, it can not coast or maintain it's velocity with out an outside force acting on it. Slingshot projectiles are always changing velocity to reach an equilibrium state between all the vector forces acting upon it. There is no area of constant velocity unless you drop the projectile from a great height and achieve terminal velocity when an equilibrium between the acceleration of gravity (9.8 meters / sec /sec) and the air resistance of the projectile.is achieved. Some would argue that even this is not possible due to minute changes in air density and the fact that gravity increases as the distance to the earth decreases. But we can still enjoy the average velocities of our shooters.
frosty2
Don't have a physics degree here, but I am pretty sure that once whatever is making the projectile (ammo or baseball) departs what is thrusting it forward (band or pitchers arm) it instantly starts slowing down, with nothing pushing or pulling it forward it can't go faster (air resistance and gravity).
I'm actually a baseball fan and a catcher on an adult wood bat league up here in NY. Pitchers can do amazing things using the laces of a ball and air resistance, but they simply cannot do anything to make the ball go faster once it leaves their hand. They can put spin on it to make it drop, curve, or cut, but not go faster. They can do one thing which might make it "appear" to go faster, which is if you throw a 4 seem fastball, it will keep the ball on the same plane vertically longer which might make it appear faster, but it isn't really faster, it just stays UP longer.
Baseball physics can be funny. Let's take a hitter instead of a pitcher. Should a hitter hit a 50oz bat that he can only swing 20mph, or should he use a wiffle ball bat which he cans swing 100mph but when it contacts the ball it send the bat backwards instead of the ball forwards. The variables are great but in theory a batter wants to use the heaviest bat he can swing with a high velocity. Then once he has that, if he wants the ball to go further he wants to hit the ball in a manner which puts back spin on it to keep it in the air long enough to get out of the park. Think tennis, top spin allows them to hit the ball fast and then it dives down to stay in the other end of the court, If the tennis player puts back spin on it, it tends to go slower, but it can often goes long and out of bounds because it slowly floats a long time and stays in the air longer.
Of course I imagine most of these dynamics are taken away in slingshots as most of the ammo is smooth. I can tell you clay balls definitely curve, but we didn't make them perfectly round or perfectly smooth. But if normal ammo is perfectly smooth and round and the release from the pouch puts no rotation on the shot then the balls speed and distance is totally dependent on its exit speed, weight, air flow and gravity. However it should go relatively straight (side winds)! Unlike a baseball that has laces so the wind moves it all over the place (aka knuckle ball).
But I still believe that the point you are looking for, where it is no longer accelerating, nor slowing is the exact point where the bands stop 'pulling' the ammo forward, which in most cases is probably actually the length of where your bands connect to the fork and the pouch. I think if we could slow things down enough we could see that at that "slack"' point, the ammo disengages from the pouch and the pouch is just following the ammo through at that point. I could be wrong, and if so, would definitely like to understand better.
O, and if you ask why the ammo disengages then, it would because the force propelling both the pouch and the ammo forward stops at that point and the ball has less air resistance than the pouch, so the pouch begins to slow fast.
Hope this helps, hope it makes sense, hope it is correct, but if it isn't, I don't mind learning something new! Or thinking a different way.
I'm actually a baseball fan and a catcher on an adult wood bat league up here in NY. Pitchers can do amazing things using the laces of a ball and air resistance, but they simply cannot do anything to make the ball go faster once it leaves their hand. They can put spin on it to make it drop, curve, or cut, but not go faster. They can do one thing which might make it "appear" to go faster, which is if you throw a 4 seem fastball, it will keep the ball on the same plane vertically longer which might make it appear faster, but it isn't really faster, it just stays UP longer.
Baseball physics can be funny. Let's take a hitter instead of a pitcher. Should a hitter hit a 50oz bat that he can only swing 20mph, or should he use a wiffle ball bat which he cans swing 100mph but when it contacts the ball it send the bat backwards instead of the ball forwards. The variables are great but in theory a batter wants to use the heaviest bat he can swing with a high velocity. Then once he has that, if he wants the ball to go further he wants to hit the ball in a manner which puts back spin on it to keep it in the air long enough to get out of the park. Think tennis, top spin allows them to hit the ball fast and then it dives down to stay in the other end of the court, If the tennis player puts back spin on it, it tends to go slower, but it can often goes long and out of bounds because it slowly floats a long time and stays in the air longer.
Of course I imagine most of these dynamics are taken away in slingshots as most of the ammo is smooth. I can tell you clay balls definitely curve, but we didn't make them perfectly round or perfectly smooth. But if normal ammo is perfectly smooth and round and the release from the pouch puts no rotation on the shot then the balls speed and distance is totally dependent on its exit speed, weight, air flow and gravity. However it should go relatively straight (side winds)! Unlike a baseball that has laces so the wind moves it all over the place (aka knuckle ball).
But I still believe that the point you are looking for, where it is no longer accelerating, nor slowing is the exact point where the bands stop 'pulling' the ammo forward, which in most cases is probably actually the length of where your bands connect to the fork and the pouch. I think if we could slow things down enough we could see that at that "slack"' point, the ammo disengages from the pouch and the pouch is just following the ammo through at that point. I could be wrong, and if so, would definitely like to understand better.
O, and if you ask why the ammo disengages then, it would because the force propelling both the pouch and the ammo forward stops at that point and the ball has less air resistance than the pouch, so the pouch begins to slow fast.
Hope this helps, hope it makes sense, hope it is correct, but if it isn't, I don't mind learning something new! Or thinking a different way.
The explanation makes complete Logic. But, I have wondered and perhaps this has happend to others, while shooting some cans that are difficult to penetrate I have attempted to get 3 feet away thinking this would do it. It did not so I backed off 3 more feet and Bingo. So my thinking was that there is a temporary momentary point of increase of velocity that must occur after the pouch. Or maybe the occurance I described is just a Fluke. But, your xplanation sounds Right.
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LOL, if your 'muzzle' velocity is less than your projectile's terminal velocity you've got problems! I'm pretty sure when I was like 6, my brother and I would do just that with our truly awful home-made 'bows'!I've modelled this and the ball can speed up, but only if it starts slow and drops a long way.![]()
Normally though, it stops accelerating just after the band goes slack. There's high speed video on my YouTube channel.
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This perked my interest so I set up my crono and did some shooting. I set so the slingshot was 3,6,9,and 12 feet from the front of the crono. I shot three shots from each distance and averaged the results. I am shooting 1 inch untapered bands that are 6 1/2 inchs from the fork to the knot. I shot marbels that are 60 grains.
I pull to 32 inches.
3 feeet avg. 223.3 fps
6 feet avg. 222 fps
9 feet avg. 218 fps
12 feet avg. 213.3 fps
You can see how fast the marble slows down in 9 feet it is down to 95 percent of its maximum speed.
I was also thinking about the question of exceleration. I think the ball has reached its maximum speed within the first couple of inches after release from your finger and even then is starting to pull away from the pouch. What we need is a true high speed video of the ball and pouch from the moment of release to the forks. While I was shooting I also did some shooting pulling the same bands to different lenghths.
pulled to 12 inches speed 155 fps
pulled to 28 inches speed 174 fps
pulled to 30 inches speed 218.5 fps
pulled to 32 inches speed 224 fps
You can see by the time the pouch has traveled only 2 inches the bands only have enough energy to shoot the marble at 218.5 fps but the marble is already at 224 fps so it has already started to leave the pouch.
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I pull to 32 inches.
3 feeet avg. 223.3 fps
6 feet avg. 222 fps
9 feet avg. 218 fps
12 feet avg. 213.3 fps
You can see how fast the marble slows down in 9 feet it is down to 95 percent of its maximum speed.
I was also thinking about the question of exceleration. I think the ball has reached its maximum speed within the first couple of inches after release from your finger and even then is starting to pull away from the pouch. What we need is a true high speed video of the ball and pouch from the moment of release to the forks. While I was shooting I also did some shooting pulling the same bands to different lenghths.
pulled to 12 inches speed 155 fps
pulled to 28 inches speed 174 fps
pulled to 30 inches speed 218.5 fps
pulled to 32 inches speed 224 fps
You can see by the time the pouch has traveled only 2 inches the bands only have enough energy to shoot the marble at 218.5 fps but the marble is already at 224 fps so it has already started to leave the pouch.
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There is some high speed photos of the shot leaving the pouch (by Joergs I think). It did not look to me like the shot was completely out of the pouch when the pouch was going past the forks. It looked like the shot was starting to leave the pouch at about the time that the bands had reflexed to there orginal length. -- Tex
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I agree with what you say. I think after a couple of inches the ball is slowly moving away from the pouch. The first impules of power is only a couple of inchs and the ball and pouch start to seperate. The videos we are using do not have the clarity we need. We need someone with a strob setup and a overhead view of the pouch and ball to see what actually happens.
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I made a shield for my crono this morning so I could shoot thru it at 10 yards. I got an average speed of 208 fps at ten yards as compared to 223.3 at 3 feet. I didn't have the nerve to shoot 1/2 steel at it from that distance.
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I agree with everything you said besides the last statement. First as many are saying the max speed is when the ball reaches the point where the bands are no longer pulling it forward. So after 2 inches the bands still have a long ways to go. Secondly if what you're saying is correct then if you were to pull the bands to 32 inches and have something to stop them at 30 inches that it will clock at 224 fps. Feel free to try that if you would like but I think anyone with common physics knowledge would realize that isn't right. The reason you get 224 out of a longer draw is because the acceleration period is longer to where the bands aren't pulling. Not the 2 inches you pulled past what shot 218 fps. So really what you got was an added 6 fps in the 2 inches not 224 fps in 2 inches.
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