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Posted: 3/20/2017 11:51:56 AM EDT
[#1]
Quoted:
A stupid Sci-Fi question for people smarter than me. You have an archer in Zero G and have an bow with arrow nocked. The archer releases. What happens to the archer. Does he stay somewhat static? Does the release of the bow's energy push him in any specific direction? He would move slowly off in the direction 180 degrees from the arrow. Whenever you accelerate mass in one direction, you go in the other direction. He would go slowly because he is much more massive than the arrow, hence he would accelerate to a much lower velocity. |
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Posted: 3/20/2017 11:54:06 AM EDT
[#2]
Quoted:
A stupid Sci-Fi question for people smarter than me. You have an archer in Zero G and have an bow with arrow nocked. The archer releases. What happens to the archer. Does he stay somewhat static? Does the release of the bow's energy push him in any specific direction? Equal and opposite. The archer will drift backwards, likely tumbling unless the arrow was aligned with his center of mass. |
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Posted: 3/20/2017 11:57:19 AM EDT
[#3]
Quote HistoryQuoted:
He would move slowly off in the direction 180 degrees from the arrow. Whenever you accelerate mass in one direction, you go in the other direction. He would go slowly because he is much more massive than the arrow, hence he would accelerate to a much lower velocity. |
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Posted: 3/20/2017 12:00:33 PM EDT
[#4]
Quote HistoryQuoted:
He would move slowly off in the direction 180 degrees from the arrow. Whenever you accelerate mass in one direction, you go in the other direction. He would go slowly because he is much more massive than the arrow, hence he would accelerate to a much lower velocity. Also assuming archer loosed the arrow in a direction other than 180* away from the surface archer was standing on. Ignoring elastic/inelastic properties if all materials involved. |
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Posted: 3/20/2017 12:03:34 PM EDT
[#5]
Quote HistoryQuoted:
Assuming static/dynamic friction was the only thing 'holding' archer to the surface 'under' his feet. Also assuming archer loosed the arrow in a direction other than 180* away from the surface archer was standing on. Ignoring elastic/inelastic properties if all materials involved. |
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Posted: 3/20/2017 12:37:23 PM EDT
[#6]
Quote HistoryQuoted:
It seems you're also assuming a surface. Missed that one. 
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Posted: 3/20/2017 12:39:19 PM EDT
[#7]
But what if the archer was standing on a treadmill?
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Posted: 3/20/2017 1:31:33 PM EDT
[#8]
Quote HistoryQuoted:
But what if the archer was standing on a treadmill? Answer: Bungee Run!
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Posted: 3/20/2017 3:27:05 PM EDT
[#9]
Quote HistoryQuoted:
Assuming static/dynamic friction was the only thing 'holding' archer to the surface 'under' his feet. Also assuming archer loosed the arrow in a direction other than 180* away from the surface archer was standing on. Ignoring elastic/inelastic properties if all materials involved. Nice try to demonstrate your erudition. |
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Posted: 3/20/2017 4:27:52 PM EDT
[#10]
I'm more interested in how the arrow will perform without the friction of a gas helping it stay stabilized.
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Posted: 3/20/2017 4:57:37 PM EDT
[#11]
Quote HistoryQuoted:
I'm more interested in how the arrow will perform without the friction of a gas helping it stay stabilized. OP simply specified "zero gravity". |
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Posted: 3/20/2017 5:01:48 PM EDT
[#12]
Quote HistoryQuoted:
I'm more interested in how the arrow will perform without the friction of a gas helping it stay stabilized. |
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Posted: 3/20/2017 5:24:32 PM EDT
[#13]
Quote HistoryQuoted:
Why are you assuming there is no gas? he said zero gravity, he didn't say "in outer space" You're right. |
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Posted: 3/20/2017 9:36:50 PM EDT
[#14]
Quoted:
A stupid Sci-Fi question for people smarter than me. You have an archer in Zero G and have an bow with arrow nocked. The archer releases. What happens to the archer. Does he stay somewhat static? Does the release of the bow's energy push him in any specific direction? Edit to add: Let's assume outer space. I'm reading the Expanse books which brought this question to mind. |
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Posted: 3/21/2017 8:14:22 AM EDT
[#15]
Quote HistoryQuoted:
Edit to add: Let's assume outer space. I'm reading the Expanse books which brought this question to mind. But that also means that it won't have drag to slow it down as it tumbles. Unless of course your nock is on a swivel and you find a way to spin-stabilize the arrow before firing. |
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Posted: 3/21/2017 8:20:50 AM EDT
[#16]
If right handed, the archer would drift forwards and start spinning left.
Unlike a firearms recoil, the stored energy is in the string, which flies forwards. Arrow gets released from nock when the bow string stops it's forward movement due to tension from the bow. That forward energy is also what would pull the archer forwards. |
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Posted: 3/21/2017 8:25:36 AM EDT
[#17]
Quote HistoryQuoted:
If right handed, the archer would drift forwards and start spinning left. Unlike a firearms recoil, the stored energy is in the string, which flies forwards. Arrow gets released from nock when the bow string stops it's forward movement due to tension from the bow. That forward energy is also what would pull the archer forwards. You are saying that the archer will move in the same direction as the arrow he fired. Chew on that for a minute. Ignore the shirtless man. About a minute in he switches to a longbow, which you can see is extending and compressing his wrist as the string undulates, but the overall sum of all of that motion will be equal and opposite to the arrow leaving the bow. F=M*A. You can't accelerate the arrow in one direction without accelerating the archer in the opposite direction.  slow motion bow & arrow, archers paradox |
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Posted: 3/21/2017 8:45:05 AM EDT
[#18]
Quote HistoryQuoted:
You can't accelerate the arrow in one direction without accelerating the archer in the opposite direction.  https://www.youtube.com/watch?v=EfyzL9C-8WY |
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Posted: 3/21/2017 9:00:42 AM EDT
[#19]
Quote HistoryQuoted:
You are overthinking it, and doing a terrible job of it. Upon release, the string and limbs ondulate forward at 100 energy, but due to absorbtion by the limbs, wouldn't the rearward bounce be reduced, so like 100 forward, 90 rearward, 80 forward, 70 rearward, etc? Wouldn't that still mean that the forward energy is greater than the rearward? Are there any vids on a freestanding bow getting shot, to show which way the bow falls? |
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Posted: 3/21/2017 9:26:01 AM EDT
[#20]
Quote HistoryQuoted:
Then I may as well continue, so you guys can show me error of my ways. Upon release, the string and limbs ondulate forward at 100 energy, but due to absorbtion by the limbs, wouldn't the rearward bounce be reduced, so like 100 forward, 90 rearward, 80 forward, 70 rearward, etc? Wouldn't that still mean that the forward energy is greater than the rearward? Are there any vids on a freestanding bow getting shot, to show which way the bow falls? A force over a length of time is an impulse, and the impulse applied to the arrow is also applied to the archer. If an archer fired an arrow with his bow hand open (and not other support), yes the bow would fall forwards out of his hand, but before that happened, it was being pushed back into his hand by the reactionary force from accelerating the arrow. Without the archer's hand, the bow would fly backwards. You don't notice the wrist compression during firing in high speed videos because the arm is already fully compressed under the draw weight. Have you ever fired a crossbow? Crossbows have recoil just like a firearm, and that's just a bow with a stock.  Barrnet crossbow : Bcx recoil |
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Posted: 3/21/2017 11:34:58 AM EDT
[#21]
Quote HistoryQuoted:
Then I may as well continue, so you guys can show me error of my ways. Upon release, the string and limbs ondulate forward at 100 energy, but due to absorbtion by the limbs, wouldn't the rearward bounce be reduced, so like 100 forward, 90 rearward, 80 forward, 70 rearward, etc? Wouldn't that still mean that the forward energy is greater than the rearward? Are there any vids on a freestanding bow getting shot, to show which way the bow falls? Accelerating that mass, "pushing against it" (or its inertia) if you will, causes an equal and opposite reaction. All that other shit is irrelevant to the original question. |
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Posted: 3/21/2017 11:34:59 AM EDT
[#22]
Quote HistoryQuoted:Have you ever fired a crossbow? Crossbows have recoil just like a firearm, and that's just a bow with a stock.
https://www.youtube.com/watch?v=MM35GDq4CgA |
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Posted: 3/21/2017 11:37:23 AM EDT
[#23]
Typical GD.
1. Guy asks question. 2. Guy gets answers to question. 3. At least half of answers are pure horseshit, or just plain wrong. 4. Poor guy who asked question still does not know the correct answer. |
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Posted: 3/21/2017 11:54:47 AM EDT
[#24]
Quote HistoryQuoted:
Typical GD. 1. Guy asks question. 2. Guy gets answers to question. 3. At least half of answers are pure horseshit, or just plain wrong. 4. Poor guy who asked question still does not know the correct answer. If the archer is not anchored to anything, i.e. he is floating, then conservation of momentum dictates that he will have an overall movement opposite to the direction of the arrow (his momentum will be equal to, and opposite, that of the arrow). This will be relatively slow, as momentum is mass x velocity, and the archer's mass is probably a thousand times that of the arrow, resulting in the archer's velocity being one one-thousandth of the arrow's. The archer may spin or tumble as well, depending on the angle the bow was held with respect to the body and where the reverse path of the arrow points with respect to the archer's center of mass. Mike |
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Posted: 3/21/2017 11:57:05 AM EDT
[#25]
Quote HistoryQuoted:
The correct answer is in there somewhere, although it may be buried in the noise...
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Posted: 3/21/2017 11:57:12 AM EDT
[#26]
Quote HistoryQuoted:
The correct answer is in there somewhere, although it may be buried in the noise. If the archer is not anchored to anything, i.e. he is floating, then conservation of momentum dictates that he will have an overall movement opposite to the direction of the arrow (his momentum will be equal to, and opposite, that of the arrow). This will be relatively slow, as momentum is mass x velocity, and the archer's mass is probably a thousand times that of the arrow, resulting in the archer's velocity being one one-thousandth of the arrow's. The archer may spin or tumble as well, depending on the angle the bow was held with respect to the body and where the reverse path of the arrow points with respect to the archer's center of mass. Mike |
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Posted: 3/21/2017 4:20:34 PM EDT
[#27]
Quote HistoryQuoted:
OP said only that the archer was in zero G, not one frigging word about "standing" or "surface". Nice try to demonstrate your erudition. I accept that. Assumptions can be ill advised or lead to false shortcuts. You assumed archer had much greater mass than the arrow. If the arrow has greater mass than you assumed - archer wouldn't be be constrained to move more slowly than the arrow. If they had the same mass they would move apart at equal speeds. I'm not going to posit that the arrow might be more massive, and the implications that would have on the velocity of archer. Assumptions are convenient, and don't fit all situations. Can we still be friends? 
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Posted: 3/21/2017 5:41:49 PM EDT
[#28]
Quote HistoryQuoted:
Can we still be friends? What the hell ........ it's GD and we should all be here in the spirit of friendship, camaraderie, and all that sort of thing. When it's no longer fun it's time to step away. I will add as a parting shot, that most archers are quite a bit more massive than their arrows. It works out better that way. |
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Posted: 4/19/2017 8:38:46 PM EDT
[#29]
Quote HistoryQuoted:
He would move slowly off in the direction 180 degrees from the arrow. Whenever you accelerate mass in one direction, you go in the other direction. He would go slowly because he is much more massive than the arrow, hence he would accelerate to a much lower velocity. A limb bow will do as you say as would most older bows but the new compound bows with parallel limbs may not. Think limbs impart their energy perpendicular to the arrow flight. The design is such that the recoil of the bow is not back toward the shooter. There is still the equal/opposite thing going on but the recoil is redirected and absorbed by the bow. |
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Posted: 4/20/2017 8:15:17 AM EDT
[#30]
Quote HistoryQuoted:
I think they type of bow needs to be taken into account. A limb bow will do as you say as would most older bows but the new compound bows with parallel limbs may not. Think limbs impart their energy perpendicular to the arrow flight. The design is such that the recoil of the bow is not back toward the shooter. There is still the equal/opposite thing going on but the recoil is redirected and absorbed by the bow. He is still accelerating mass (arrow) in one direction so he will travel in the opposite direction. |
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Posted: 4/21/2017 8:12:25 AM EDT
[#31]
The type of bow doesn't matter at all. Conservation of momentum means that the shooter (including the bow in his hand) and the arrow will have the same magnitude but opposite directions of momentum. How the bow is shaped or what movement it makes is irrelevant, because it is part of the "momentum package" that is the shooter, so long as he doesn't drop it.
Mike |
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Posted: 4/21/2017 8:14:18 AM EDT
[#32]
Quote HistoryQuoted:
so long as he doesn't drop it. Mike
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Posted: 4/21/2017 9:23:14 AM EDT
[#33]
I asked my son, a competitive archer. He seemed to think the bow would actually travel forward with the recoil.
I still think the design does matter. Any design that cancels out the recoil is absorbing the energy opposite of the arrow flight. A long bow absorbs pretty much nothing so I don't don't doubt the assumption that the archer would b pushed back when using one of that design. |
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Posted: 4/21/2017 9:54:03 AM EDT
[#34]
Quote HistoryQuoted:
I asked my son, a competitive archer. He seemed to think the bow would actually travel forward with the recoil. I still think the design does matter. Any design that cancels out the recoil is absorbing the energy opposite of the arrow flight. A long bow absorbs pretty much nothing so I don't don't doubt the assumption that the archer would b pushed back when using one of that design. A parallel limb bow will put less impulse into your hand, but it will also not "snatch" forward at the end of the stroke as much. A caveat to this comparison is energy lost to friction and dampened vibration (sound, heat, ect). Regardless, if the arrow leaves at the same velocity, the archer will travel at the same relative velocity, independent of bow design. |
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Posted: 4/21/2017 1:25:39 PM EDT
[#35]
Sounds like an interesting discussion point for a Star Talk Radio podcast.
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Posted: 4/21/2017 6:01:09 PM EDT
[#36]
Quote HistoryQuoted:
I asked my son, a competitive archer. He seemed to think the bow would actually travel forward with the recoil. I still think the design does matter. Any design that cancels out the recoil is absorbing the energy opposite of the arrow flight. A long bow absorbs pretty much nothing so I don't don't doubt the assumption that the archer would b pushed back when using one of that design. It does not matter HOW the mass of the arrow leaves. The momentum of the system must sum to zero (or at least a constant) at all times. The arrow is going one way and the archer is going in the opposite direction so the momentum of the two sums to zero. Since the bow is not exerting force on the archer at their center of mass their will be both translation and rotation of the archer. |
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Posted: 7/3/2017 7:13:01 PM EDT
[#37]
Quote HistoryQuoted:
Though interestingly the arrow would likely MISS the target, because there wouldn't be a parabolic effect on the arrow. IE it would hit high or completely miss. |
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Posted: 7/13/2017 3:10:01 PM EDT
[#38]
Quote HistoryQuoted:
Assuming static/dynamic friction was the only thing 'holding' archer to the surface 'under' his feet. Also assuming archer loosed the arrow in a direction other than 180* away from the surface archer was standing on. Ignoring elastic/inelastic properties if all materials involved. However, your idea of firing at an angle to that surface is a good one. I think RDTCU's idea of being tumbled is a good contribution, too. My insignificant contribution - the archer will start to move as soon as he attempts to draw back the bow, not just upon release. |
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Posted: 7/14/2017 3:06:31 PM EDT
[#39]
Quote HistoryQuoted:
Even standing on a surface, without gravity, there would be no frictional force to hold the archer. However, your idea of firing at an angle to that surface is a good one. I think RDTCU's idea of being tumbled is a good contribution, too. My insignificant contribution - the archer will start to move as soon as he attempts to draw back the bow, not just upon release. The drawing of the arrow is internal forces in the system. Until there is a change in the momentum of the system (the arrow leaving at non zero velocity) no movement. He could exert force to bend the arrow with both hands and would not move either. |
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Posted: 8/17/2017 1:02:14 AM EDT
[#40]
Quote HistoryQuoted:
Nope. The drawing of the arrow is internal forces in the system. Until there is a change in the momentum of the system (the arrow leaving at non zero velocity) no movement. He could exert force to bend the arrow with both hands and would not move either. |
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Posted: 8/17/2017 1:08:38 AM EDT
[#41]
Quote HistoryQuoted:
The correct answer is in there somewhere, although it may be buried in the noise. If the archer is not anchored to anything, i.e. he is floating, then conservation of momentum dictates that he will have an overall movement opposite to the direction of the arrow (his momentum will be equal to, and opposite, that of the arrow). This will be relatively slow, as momentum is mass x velocity, and the archer's mass is probably a thousand times that of the arrow, resulting in the archer's velocity being one one-thousandth of the arrow's. The archer may spin or tumble as well, depending on the angle the bow was held with respect to the body and where the reverse path of the arrow points with respect to the archer's center of mass. Mike Some crazy British guy said this, "For every action, there is an equal and opposite reaction." To focus on the release of the arrow and not consider the drawing of the bow is an error. |
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Posted: 8/18/2017 9:28:55 AM EDT
[#42]
Quote HistoryQuoted:
To focus on the release of the arrow and not consider the drawing of the bow is an error. The only observable change in movement after drawing the bow might be spin rate, and then only if there was a non-zero spin in the first place. Angular momentum would still be conserved, but moving the bow and archer apart would likely change the moment of inertial of the system (like the classical example of the spinning ice skater pulling in her outstretched arms to increase her spin rate). Mike |
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Posted: 12/19/2017 12:21:07 AM EDT
[#43]
nm....
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