Trad Gang
Main Boards => PowWow => Topic started by: Keenan on December 31, 2006, 12:40:00 PM
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I was reading the thread about (MY bow is so fast) and I pondered a thought, What if you shot, (backwards) out of the back of a truck that was travleing at the same speed as your bow shoots. To a bystander watching along the road ,Would the arrow just apear and fall striaght down to the ground?
In theory if the speed was matched,Would the the forward motion of the bow cancle the motion of the string moving towards the rear of the truck?
If so is it the bow that is fast or the arrow? Maybe I should have some more coffee. Keenan
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Keenan, Your thinkin' to much again..... Why don't you grab your bow and go shoot some arrows LOL
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At 55 mph your vehicle is traveling at about 80 fps. Just think how fast you would be driving to find out. :bigsmyl:
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Originally posted by BigRonHuntAlot:
At 55 mph your vehicle is traveling at about 80 fps. Just think how fast you would be driving to find out. :bigsmyl:
LOL! Sounds like a Darwin Award in the making...
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gettin a headache just readin that lol
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I've seen this question before somewhere. I beleive the correct answer was prove(mathmatically) to be that the arrow would fall to the ground at point of release. Simple because they would cancle each other out.
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fall to the ground if shot backwards, double your fps if shot forward(assuming vehicle and arrow fps are the same)
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But what if you had a tail wind twice the speed of your truck? :bigsmyl:
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Arrow Speed X 3763097563587 + 2/3 of Vehicle Momentum X (arrow weight) plus ratio of 994562 @ a standard/varied/nevermind/ of 62% vertical lift = tire size minus your last haircut...round out the road conditions...invert 4/5s of the total number in rolls of toilet paper used yearly...add 974625 sq....divide by 11-teen and you get half the answer...
GOT IT NOW?...My oh my...You guys are sumthin'
>>-----> mike <-----<< :D
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Holly smokes I never knew just how mathmatical it was. Thanks now my brain hurts LOL
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Where`s Marilyn vos Savant when you really need her? Hap
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The answer is no. There are more forces in play than the momentum of the truck and bow.
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Mike:that was great! made me bust a gut!
Pointy sticks; If so then we would be inclined to think that the bow is moving backward and the string nock is stationary at the point of release,,,,,Then at the precise point of seperation of nock and string (Brace H) the string would then accelerate backward with the truck,,,,Would the friction of the nock pulling away from the string be a factor???
Ok maybe I better wander back out to the shop and give the brain a rest.......LOL Keenan
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"Where`s Marilyn vos Savant when you really need her? Hap"
:clapper:
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That means that if you shot in the direction of travel the arrow would stay on the string? :confused: :confused: :confused: :help:
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If your truck is traveling at 160 FPS slower than the speed of light. You shoot an arrow in the direction of travel at 161 FPS. Will the arrow disappear? Rusty
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I'll second the Darwind Awards! I have the site bookmarked to keep an eye on it, this could be a winner. dino
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Vermonster is correct. There are more forces at work in an equation like that.
Remember, energy is never lost, it's absorbed. Knowing this to be true, the bow is also moving as fast as the truck, but it has stored energy when drawn. Obviously upon release, that energy is imparted onto the shaft. Now the shaft has a large percentage of that stored energy that was in the bow. Therefore one has to surmise that when that shaft is subjected to the forces of release and absorbing all that energy, with a tailwind of 160fps or so (if winds were calm that day) then the arrow will definitely leave the bow with a measurable amount of velocity. Sufficient to at least travel beyond the bow and shooter.
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I say if you are traveling 160 fps and you shoot an arrow out the back (towards the rear of the truck)at 160 fps the following will be true. One second after release the arrow will be 320 fps away from the point of release. :)
BTW, they shoot cross bows from moving helicopters to dart animals. You could watch a few of the video and see what happens.
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Sounds to me like we need some good ol down to earth testing.
First we is gunna need a jacked up redneck 4x4 with the blown moter and all to be able to get them high speeds matched up. Then we's gunna need a lazy boy in the back to be saftly fastened in.
Next a good long country road so we dont be breakin no laws and plenty of mud holes to keep the crowds happy.
We is gunna be havin a raffle to see who gets to hold the conograph fer the forward test and a couple spotters fer the backward test.
And to keep things going along smoothly we is givin everybody arrows with rubber blunts to try and hit the bulleye on the truck as it flys by. LOL sounds like the start of an anuall outing...Keenan
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We'll simplify things to say that the car is a vehicle on a fixed track going exactly 160fps in a windless environment and the arrow is shot from a shooting machine set such that it will always shoot 160fps. The arrow's not going anywhere. The 160fps is relative to the platform it's being shot from, not another reference point.
In the real world some other forces might apply, but it won't go real far and might even go backward(bad release or short draw limiting speed, etc)
Vector math from physics 101...
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Gravity is working on both truck and bow. The energy is still pushing the arrow. Speed will be exactly the same.. Point of release is still the point of release. 32'per second squared.... LOL
JDS III
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If you were inside a closed tractor trailer or an airplane traveling at 160fps and shooting at a target at the back of the box or cabin you would notice nothing different (assuming you were going level and straight).
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What DG said. For certain it will travel down the length of the truck bed at 160 fps :knothead: :bigsmyl: ....Van
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This sounds like a project for MythBusters. :saywhat:
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A deputy clocked my arrow at 126mph.Converted that's about 185fps.There's no way I woulod stand in the back of a pick-up doing 126mph.But it would be fun to watch someone else try it.
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OK, I'll drive, someone hop in. You aren't using my bow though, and noone tells my wife.
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sar and meathook have it right. I took physics too.
Now, put a deer on a steel-hauling truck (one of those with the narrow one-person cab). Make that truck and the one you are on tear down the road at 160 fps and shoot the deer. The same thing will happen as would happen if the trucks were stationary.
The deer traveling at 160 fps runs into the arrow, which is stationary relative to the road. The deer's vital area passes around the arrow.
I might have a better chance that way! :biglaugh:
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Rainman couldn't do this math.
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I say the arrow falls directly to the ground. However, due to the bow having stored energy, the truck would be propelled to light speed and enter an alternate dimension where archery doesn't exist.
That'll learn'em.
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Hmmm. First, we have to ask, "Is this a Ford or a Chevy?" There was a time when I could puzzle this out, but now? Well, my bow is so fast...the string is water-cooled. The windshield best be arrow-proof!
I'll wait to see the actual testing done in JackArseIII. :bigsmyl:
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Throw out a bunch of other factors and sure, the arrow would drop.
In reality, the drag of the fletching in the vortex behind a vehicle moving that fast means that arrow is going anywhere but straight down.
Translated====I don't want to be within fifty yards of this particular experiment....
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....could you get an anti-equalibrium state where if you were going slow enough at release then accelerated that the force of the arrow would actually DRAW the bow!?!?!
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Here's another example that may add to the puzzle. NASA uses 747s on an alternating climb/dive flight cycle, trainee astronauts inside get to experience weightlessness on the dive cycle. IE relative to the interior of the plane they are weightless but the plane itself is moving real fast downwards! ? Vector physics says the arrow will drop but who would be on the truck and shooting at that speed?
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Hold my beer......Watch this!!!!!!!!
:bigsmyl:
LD
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Ok this is gettin good, Now if the truck was going 175 fps. and the bow shot an arrow at 160 fps. (out of the bacK) The arrow would in essence leave the bow travleing backwards. Then as air frction hit the fletches in arrow would flip 180 to correct flight then hit the poor fool shooting because the driver stopped to see what happened,,,Possible,!!!Keenan
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Isn't it amazing how our posts digress as hunting season winds down?
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Which broadhead is best for this: a two or three blade- or a four blade???
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Stop the insanity!!!!!!!!!!!!!!!!!!
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"If you were inside a closed tractor trailer or an airplane traveling at 160fps and shooting at a target at the back of the box or cabin you would notice nothing different (assuming you were going level and straight)".
"What DG said. For certain it will travel down the length of the truck bed at 160 fps"
This is incorrect the arrow would be standing still and the back of the truck would run into the arrow at 160 fps.
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That doesn't seem right wtpops, because the deer and the bowyer are traveling at the same speed relatively to each other the arrow speed would be the speed that the arrow hits the deer with. Think of it this way, a target and a shooter are both traveling x miles per hour on the earth as it spins in space and the arrow speed is what is measured in that instance. If you shot towards the direction the earth is rotating does your arrow speed change?
I know planes measure both ground speed and airspeed because with a strong headwind the amount of air passing over the wing could be great but I have actually been stationary, or even moving backwards, in relation to the ground.
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Yes but if you think of it this way. Put a glass window the full lenght of the truck then a spectator is standing on the side of the road, the archer releaces the arrow just as they get to the spectator. The spectator would see the arrow stand still and the back of the truck run into the arrow
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Ok now my frountal lob hurts time to go out in the back yard a shoot some arrows.
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Originally posted by wtpops:
Yes but if you think of it this way. Put a glass window the full lenght of the truck then a spectator is standing on the side of the road, the archer releaces the arrow just as they get to the spectator. The spectator would see the arrow stand still and the back of the truck run into the arrow
I wonder if that's how they filmed The Matrix.
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:knothead: :bigsmyl: ...Van
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Allow me to cut through some of the cluter here..
The one constant in this equation is that all the objects in the hypothetical scenario are all moving at the same speed before the arrow is released. Therefore it doesn't matter if you were going 200 fps or 2000 fps. It is all constant.
Therefore it is my belief that the only way that the arrow would fall directly to the ground is if the truck were accelerating so quickly that it created enough G's to be equal to the amount of energy the arrow was absorbing at the moment of release. Only in a scenario such as this do you have an opposing force on the arrow.
Right???
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Nope Troy, Ya missed the details. You would be shooting in the opposite direction as you are traveling thus causing the speeds to cancle each other out. But what do I know I started pondering this dumb thought and now I'm not sure that I knew what I thought I was thinking about when I thought it. So if I didn't know what I thought I was thinking about when I thought it was it really a thought at all,,,,Lol Keenan
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Awesome!!! I'm on muscle relaxers and pain killers for my back right now, This is clear as mudd.
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left wing or right wing fletch- straight or helical???
How far is the bed of the truck from the ground?
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What does this have to do with bowhunting?
Doesn't this belong in the hypothetical forum? :)
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O.K. but what if you use FF string?
You can't fight physics. If you shoot in the same direction, you'll just end up running over your arrow. Maybe you could try it with one of the arab "returning" arrows from that other thread?
:knothead:
If you shoot in the opposite direction, can you get better penetration on an elk with a light draw weight and a multi-blade head? :help:
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If someone was standing on the ground and launched an arrow the same direction of travel at the correct time it would appear to fall to the ground behind the truck. :)
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The problem with almost all physics problems is that it all depends on your frame of reference and your initial conditions. Physics is only absolute in an infinite frame of reference.
Let's suppose you have a truck (or better yet a 'physics sled'- a theoretical cart that moves perfectly smoothly ) moving at 160fps in a straight line. (as a vector +160fps)
Our archer on the sled fires an arrow at 160fps in the exact oposite direction of the movement of of the sled (which means, as a vector the arrow is moving at -160fps)
And let's do it all in a vacuum so there's no aerodynamic effects.
From the frame of reference of the archer, the arrow would fly off the bow at 160fps because the archer and arrow start at 0 speed relative to each other. In fact, if the archer was in a closed box on the physics sled (which moves perfectly smoothly) he would have no reason to believe (and no way to prove) that he was moving at all. It would all be the same as if he was standing on solid ground. (general relativity)
However, in the frame of reference of the ground, we see the walls of the closed box are moving at 160fps on top of the sled.
So, for the arrow to be moving at 160fps relative to the walls of the box as it appears to the archer, the arrow must have 0 velocity in the frame of reference of the ground. If the arrow had any speed at all.. say 20fps relative to the ground.. then the archer would see it moving at 180fps-- which I'm sure would be a nice surprise.
So, from the frame of reference of an observer on the ground, the arrow would stop in space (zero velocity ) and the archer would speed away from it at 160fps.
In the closed box the arrow would slam into the box moving at 160fps. If the arrow didn't hit something solid, the physics sled would move out from under it and eventually it would accellerate under gravity straight to the ground. (having 0 velocity and momentum in the ground's frame of reference)
Of course it wouldn't be quite like that because the arrow does't have infinite accelleration so through part of its flight it will actually be moving slower than 160fps which means, from the ground frame of reference, it will be 'flying backwards' even though from the archer's frame of reference it will be moving clearly away from the bow at all times.
This experiment is easy enough to do in a sciene lab with slower moving objects (which are also less affected by aerodynamics making the vacuum condition less important).
No energy is 'lost' since the moving arrow has kinetic energy in the direction of the sled and the bow adds kinetic energy in the oposite direction doing work to accellerate the arrow in a new direction. (or to DEcelerate the arrow if you're in the ground frame of reference)
The reason none of this looks like it does in real life is because we're ignoring SO many variables like aerodynamic effects--
In theory, if you stand in the box of a moving truck and throw a softball our in front of the truck you should see it fly off ahead of you (truck velocity plus throw velocity). In reality you're going to be going to the dentist because the softball will rapidly decellerate due to air resistance and you'll catch up to it with your teeth. Not pretty. (however, at no point is the softball ever moving 'towards' you in the ground frame of reference ;) )
Jake
(who just sprained a brain lobe)
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Congratulations Jake!!! Excellent analogy and discription.Especially the part about the baseball in the teeth,,,lol Keenan
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I just can't understand:And let's do it all in a vacuum so there's no aerodynamic effects.
This seems a bit silly. We don't bowhunt in vacuums.....
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Of course it's silly. We don't bowhunt from the backs of trucks moving at 109mph either. (well, maybe in Manitoba.... ;) )
It's NOT a hunting question is it?
(I was wondering why it's lasted so long in the PowWow forum )
The reason for limiting my example to a vacuum is because aerodynamic effects are VERY complicated and people were getting confused enough by the simple case.
If you want to describe the scenareo with full attention to drag forces, turbulence and so forth, be my guest. Feel free to include the myriad perturbations from the bouncing vehicle too.
Jake
(who, being simple, likes to keep examples the same way)
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What happens if you jump up in the air and shoot when you're on the vacum packed truck on a sled? ;)
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You run right into the picture of the tunnel that you painted on the rockface with your 'Acme Instant Fake Tunnel' kit.
and the roadrunner gets away... again.
Jake
(who always wonders why the coyote didn't just order out for Acme Fried Chicken)
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DG - same as if you stood still on the sled -since you're not changing your horizontal reference point relative to the sled.....
But I'm still betting on the roadrunner....
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What happens to the beer bottle thrown at the road sign in the vacumn packed, sled-truck?