KE vs. Momentum
07-16-2008, 09:35 PM
#11
Nontypical Buck
Thread Starter
Join Date: Mar 2008
Location: Texas
Posts: 2,363
RE: KE vs. Momentum
ORIGINAL: im ocd
I've had pass through shots on several deer (at22 yards or less) with about 60# of KE / .41 momentum.
I've had pass through shots on several deer (at22 yards or less) with about 60# of KE / .41 momentum.
07-16-2008, 09:39 PM
#12
Nontypical Buck
Thread Starter
Join Date: Mar 2008
Location: Texas
Posts: 2,363
RE: KE vs. Momentum
ORIGINAL: SwampCollie
This is the third time today that I've gotten to break out my picture! A hat trick for the Trick Pony!
This topic has been argued and fought over and closed and banned and reopened again. Its old hat around here. Use that search function and you'll read all the debate and banter you care to.
This is the third time today that I've gotten to break out my picture! A hat trick for the Trick Pony!
This topic has been argued and fought over and closed and banned and reopened again. Its old hat around here. Use that search function and you'll read all the debate and banter you care to.
07-16-2008, 09:49 PM
#13
Fork Horn
Join Date: Jul 2008
Location: Very S. Indiana
Posts: 155
RE: KE vs. Momentum
ok if two objects lets say square boxes that weigh the same and are traveling the same speed they have the same kinetic energy. right? ok now say one box is in the shape of a upright door and the other is a long narrow box like a pole...still with me?.. ok now they both are traveling at the same speed now but down range due to friction the door shape will slow and the more compactpole shape has lost less and therefore will have more momentum at impact point. Follow? ok the more it weighs the more stored energy it has. like the ton of bricks and the ton of feathers senerio..
07-16-2008, 09:49 PM
#14
Nontypical Buck
Join Date: Aug 2006
Location: Southern MD
Posts: 2,520
RE: KE vs. Momentum
ORIGINAL: TexasBowHunter
where else would I go to find out a formula or to learn about momentum?
where else would I go to find out a formula or to learn about momentum?
07-16-2008, 09:54 PM
#15
Nontypical Buck
Thread Starter
Join Date: Mar 2008
Location: Texas
Posts: 2,363
RE: KE vs. Momentum
ORIGINAL: bowdaddy1964
ok if two objects lets say square boxes that weigh the same and are traveling the same speed they have the same kinetic energy. right? ok now say one box is in the shape of a upright door and the other is a long narrow box like a pole...still with me?.. ok now they both are traveling at the same speed now but down range due to friction the door shape will slow and the more compactpole shape has lost less and there fore will have more momentum at impact point. Follow?
ok if two objects lets say square boxes that weigh the same and are traveling the same speed they have the same kinetic energy. right? ok now say one box is in the shape of a upright door and the other is a long narrow box like a pole...still with me?.. ok now they both are traveling at the same speed now but down range due to friction the door shape will slow and the more compactpole shape has lost less and there fore will have more momentum at impact point. Follow?
07-16-2008, 09:57 PM
#17
Nontypical Buck
Thread Starter
Join Date: Mar 2008
Location: Texas
Posts: 2,363
RE: KE vs. Momentum
ORIGINAL: brucelanthier
http://en.wikipedia.org/wiki/Momentum
ORIGINAL: TexasBowHunter
where else would I go to find out a formula or to learn about momentum?
where else would I go to find out a formula or to learn about momentum?
07-17-2008, 05:39 AM
#18
Join Date: Jun 2008
Location: USA
Posts: 393
RE: KE vs. Momentum
ORIGINAL: TexasBowHunter
Yes sir totally....What I want to know, for example a couple of posts before yours "im ocd" posted a stated value of .41for his momentum, I want to know the formula for momentum. How did he get that value.I have searched this forum and the internet tono avail....I thought someone on here would know the formula for momentum!!!!
ORIGINAL: bowdaddy1964
ok if two objects lets say square boxes that weigh the same and are traveling the same speed they have the same kinetic energy. right? ok now say one box is in the shape of a upright door and the other is a long narrow box like a pole...still with me?.. ok now they both are traveling at the same speed now but down range due to friction the door shape will slow and the more compactpole shape has lost less and there fore will have more momentum at impact point. Follow?
ok if two objects lets say square boxes that weigh the same and are traveling the same speed they have the same kinetic energy. right? ok now say one box is in the shape of a upright door and the other is a long narrow box like a pole...still with me?.. ok now they both are traveling at the same speed now but down range due to friction the door shape will slow and the more compactpole shape has lost less and there fore will have more momentum at impact point. Follow?
I intentionally gave a momentum value the first time withoutproviding arrow weight or speed.
IME many times in this type of discussion people will say a *** grainarrow is too light, or they want more momentum than a light arrow carries, when they don't know how to determine momentum to make comparisons in the first place.
I wasn't involved in the other discussion or any previous ones, so I'll give my examples here:
In my example of 60 LB of KE with a momentum of .41 here is my arrow:
315 grain arrow @ 294 fps (I was shooting a 60# 29'' Mathews LX at the time)
KE: 294x294=x315=??????????/450240= 60
Momentum is (weight x speed/225120) 315x294=???????? / 225120 = .41
People would tell mea 315 gr.arrow did not carry enough momentum, when they had no idea how mich it actually had. [:'(]I've been through it before and here is how it works:
First I toss out a little bait...
Do you think a 520 grain arrow is heavy enough?
Traditional shooters typically have lots of momentum right?
Drop some data:
Aug. 06 Bowhunting World. 17 recurve bows tested. Average draw weight 59.8# Average KE 36.8#
Aug. 07 Bowhunting World 13 longbows tested. Average draw weight 60.7# Average KE 34.9#
Total of 30 traditional bows tested with an average draw weight of about 60.7# Average KE 35.8#
The average speed of the traditional bows is 176.3 fps with a 520 gr. arrow. Momentum = .407
My bow shoots a 315 gr. arrow @ 294 fps = .441 momentum
My light arrow carries considerably more KE and and more momentum than an accepted standard. [:@]
After I post that little bit of information the typical response will be, "I still wouldn't use an arrow that light" or "nobody I know who has been hunting a long time and killed a lot of deer uses an arrow that light". They go from data based to opinion based when data doesn't agree with their position. It did not matter that I had already gotten pass through shots with the combination. Finally, they might resortto telling me the deer I was shooting were smaller than their deer.
I don't have an interest in debating momentum so I simply laid out all the cards at once.
Now, I'm using a 350 grain arrow at 311 fps, to me, it has lots of KE / momentum.[8D]
07-17-2008, 06:09 AM
#19
Nontypical Buck
Thread Starter
Join Date: Mar 2008
Location: Texas
Posts: 2,363
RE: KE vs. Momentum
ORIGINAL: im ocd
TexasBowHunter:
I intentionally gave a momentum value the first time withoutproviding arrow weight or speed.
IME many times in this type of discussion people will say a *** grainarrow is too light, or they want more momentum than a light arrow carries, when they don't know how to determine momentum to make comparisons in the first place.
I wasn't involved in the other discussion or any previous ones, so I'll give my examples here:
In my example of 60 LB of KE with a momentum of .41 here is my arrow:
315 grain arrow @ 294 fps (I was shooting a 60# 29'' Mathews LX at the time)
KE: 294x294=x315=??????????/450240= 60
Momentum is (weight x speed/225120) 315x294=???????? / 225120 = .41
People would tell mea 315 gr.arrow did not carry enough momentum, when they had no idea how mich it actually had. [:'(]I've been through it before and here is how it works:
First I toss out a little bait...
Do you think a 520 grain arrow is heavy enough?
Traditional shooters typically have lots of momentum right?
Drop some data:
Aug. 06 Bowhunting World. 17 recurve bows tested. Average draw weight 59.8# Average KE 36.8#
Aug. 07 Bowhunting World 13 longbows tested. Average draw weight 60.7# Average KE 34.9#
Total of 30 traditional bows tested with an average draw weight of about 60.7# Average KE 35.8#
The average speed of the traditional bows is 176.3 fps with a 520 gr. arrow. Momentum = .407
My bow shoots a 315 gr. arrow @ 294 fps = .441 momentum
My light arrow carries considerably more KE and and more momentum than an accepted standard. [:@]
After I post that little bit of information the typical response will be, "I still wouldn't use an arrow that light" or "nobody I know who has been hunting a long time and killed a lot of deer uses an arrow that light". They go from data based to opinion based when data doesn't agree with their position. It did not matter that I had already gotten pass through shots with the combination. Finally, they might resortto telling me the deer I was shooting were smaller than their deer.
I don't have an interest in debating momentum so I simply laid out all the cards at once.
Now, I'm using a 350 grain arrow at 311 fps, to me, it has lots of KE / momentum.[8D]
ORIGINAL: TexasBowHunter
Yes sir totally....What I want to know, for example a couple of posts before yours "im ocd" posted a stated value of .41for his momentum, I want to know the formula for momentum. How did he get that value.I have searched this forum and the internet tono avail....I thought someone on here would know the formula for momentum!!!!
ORIGINAL: bowdaddy1964
ok if two objects lets say square boxes that weigh the same and are traveling the same speed they have the same kinetic energy. right? ok now say one box is in the shape of a upright door and the other is a long narrow box like a pole...still with me?.. ok now they both are traveling at the same speed now but down range due to friction the door shape will slow and the more compactpole shape has lost less and there fore will have more momentum at impact point. Follow?
ok if two objects lets say square boxes that weigh the same and are traveling the same speed they have the same kinetic energy. right? ok now say one box is in the shape of a upright door and the other is a long narrow box like a pole...still with me?.. ok now they both are traveling at the same speed now but down range due to friction the door shape will slow and the more compactpole shape has lost less and there fore will have more momentum at impact point. Follow?
I intentionally gave a momentum value the first time withoutproviding arrow weight or speed.
IME many times in this type of discussion people will say a *** grainarrow is too light, or they want more momentum than a light arrow carries, when they don't know how to determine momentum to make comparisons in the first place.
I wasn't involved in the other discussion or any previous ones, so I'll give my examples here:
In my example of 60 LB of KE with a momentum of .41 here is my arrow:
315 grain arrow @ 294 fps (I was shooting a 60# 29'' Mathews LX at the time)
KE: 294x294=x315=??????????/450240= 60
Momentum is (weight x speed/225120) 315x294=???????? / 225120 = .41
People would tell mea 315 gr.arrow did not carry enough momentum, when they had no idea how mich it actually had. [:'(]I've been through it before and here is how it works:
First I toss out a little bait...
Do you think a 520 grain arrow is heavy enough?
Traditional shooters typically have lots of momentum right?
Drop some data:
Aug. 06 Bowhunting World. 17 recurve bows tested. Average draw weight 59.8# Average KE 36.8#
Aug. 07 Bowhunting World 13 longbows tested. Average draw weight 60.7# Average KE 34.9#
Total of 30 traditional bows tested with an average draw weight of about 60.7# Average KE 35.8#
The average speed of the traditional bows is 176.3 fps with a 520 gr. arrow. Momentum = .407
My bow shoots a 315 gr. arrow @ 294 fps = .441 momentum
My light arrow carries considerably more KE and and more momentum than an accepted standard. [:@]
After I post that little bit of information the typical response will be, "I still wouldn't use an arrow that light" or "nobody I know who has been hunting a long time and killed a lot of deer uses an arrow that light". They go from data based to opinion based when data doesn't agree with their position. It did not matter that I had already gotten pass through shots with the combination. Finally, they might resortto telling me the deer I was shooting were smaller than their deer.
I don't have an interest in debating momentum so I simply laid out all the cards at once.
Now, I'm using a 350 grain arrow at 311 fps, to me, it has lots of KE / momentum.[8D]
07-17-2008, 07:26 AM
#20
Giant Nontypical
Join Date: Feb 2003
Posts: 9,175
RE: KE vs. Momentum
That makes since to me and that is what I had figured. The scoop that I am trying to dig up is where did this come from, I was neck deep in this sport for a many years with no mention of momentum...
When they came out with featherweight carbon arrows, that's when we started having problems. Not nearly enough mass for reliable performance with lighter draws and/or lower performance bows. Bows that did just fine with arrows with some mass to them.
It was the speed freak 3D clowns - high draw weight, low arrow weight for maximum speed - that brought the things off the target range and into the woods, wondering whether they could get those soda straw arrows to work. Well, they found out that their little arrows would often pass through a deer. That's when folks tried to figure out how the hell that could be possible, and the KE/momentum debate was born.
And I'm not going to get into it again. It just reminds me how ignorant speed freaks really are about things... like physics.
You asked for the formula for momentum. It's too unwieldy for everyday use. I've got a penetration index I like that came from a magazine some years ago. Weight(in grains) X Speed (in FPS) / 10,000. It's weighted toward the momentum side because it doesn't square velocity. Quick and easy instead of having to remember all those formulae.
Say you've got a 550 grain arrow at 200 fps. It has an index of 11. A 350 gn arrow at 300 fps figures out at 10.5. To a thinking man, it tells you how an old recurve can zip a hefty arrow through on large game just as easily, or maybe more easily, than a high performance compound with that has far greater speed and KE, but ultralight arrows.
