RE: Who said that physics wasn't fun?
 

I may be wrong but to get 125 gr 2 blade heads,I was going to have to go bigger in cutting diameter.That was not the direction I wanted to go.Trajectory wasn't even a thought on the issue of head weight.She also already has wraps.

Yes,I could get her over 400 but I really don't think it would be necessary.


I also did not want vanes.We needed the feathers for the 2 bladers and to help with the passthrough if it got to the feathers.


It already looks like a rainbow so going up 200 grains would make her have to nail the yardage,even at 20 yards.It would also be impossible to match spine.


We WILL NOT hunt anything bigger than deer.I wouldn't even think of hunting Elk with that setup.

RE: Who said that physics wasn't fun?
 

Just for the record, I never said I havent wounded and animal. It happens, and if you hunt long enough it probaly will happen. I did say that I never lost an animal do to lack of penetration. Ok that being said ARTHUR P, you argue the fact that a 25 grain heavier broadhead wont do didly sqaut for TFOX's daughter set up, so why have to increase just to make a minimum weight if what she is shooting already works.

RE: Who said that physics wasn't fun?
 

There is alot more to penetration than just momentum from a heavy arrow. Those of you who keep demanding everyone must shoot an arrow that weighs over 400 grains or more are ignorant. Depending on the set up a 365 grain arrow can penetrate as much or more than a 400. So many factors go into penetration, KE and Momentum are just two of many. Broadhead style, sharpness, arrow diameter, broadhead cutting diameter, what type of animal, distance, arrow flight, shot angle, weather the animal is tense or not, and the list goes on and on.

Arthur P, Im not sure what you hunt. Really I dont care how heavy of an arrow you shoot, thats your choice and that is prefectly fine, but Ive killed several puny deer that field dress over 250lbs with a 365 grain arrow.I dontsee an additional 35 grains making a whole lot of difference.

Ill quote you here,

Do light arrows work? IF you're knowledgeable enough touse the proper equipment and choose the right broadhead for the amount of power your equipment delivers... IF you're experienced and know how to control yourself under the stress of the moment to make a clean shot... IF you're patient and refuse to take anything but ideal shots... IF you're skilled enough and able to place your shots properly...

Shouldnt all bowhunters do that, regardless of arrow weight. Enough said.

RE: Who said that physics wasn't fun?
 

You stated that both have the same velocity. Therefore, the larger projectile will have both a higher KE and momentum.

You did leave one thing out though. p=mv is for objects moving only in a straight line. An arrow travels in the X and Y coordinate. Therefore, it has 2 compenents. Momentum is a vector quantity. Momentum in the X and Y coordinates. Since the heavier arrow has a larger arc the momentum in the X direction will be reduced compared to the lighter arrow. p now equals = m(v cos angle)
example 1
450 gr @ 280 fps angle of 15 deg
450(280 cos 15)
450(270) = 121,500

example 2
390 gr @ 305 fps angle of 10 deg
390(305 cos 10)
390(300) = 117,000

117,000/121,500 = .096 %

Obviously, this is an example. You can run this example with real values and Ibet the diffrence is not as great as people keep quoting.
People keep talking about momentum now that the lighter arrows have matched or surpased KE of the heavier arrow. And if you are going to quote an equationuse the one for the right application.

I knew the 10 yrs of college would pay off.

RE: Who said that physics wasn't fun?
 

Oh puhleeze... mometum is in the x and y coordinate?? Say what? A projectile travels in an arc, called a parabola. The path of a parabola can be depicted on an coordiante plane, using x and y coordinates. I know that sounds condesending, only because it is.

Velocity is a vector quantity. Since momentum is the product of a scalar quantity (mass) and a vector quantity (velocity) it to is a vector quanity. The same argument can be made about kinetic energy.

Since a projectile travels in a parabolic path it does, in fact, have horizontal and vertical components. The horizontal compent of velocity on a projectile is constant. The vertical component of velocity, however is not (a constant, the gravity thing). True, both the vertical and horizontal components of velocity can be calculated as a fucntion of the intial velocity of the projectile and the angle at which it was fired.
As such, both the vertical and horizontal components of momentum can be calculated as well. The question becomes, so what??
When two projectiles strike a target, the projectile with the greater momentum, p=mv,(all else being equal, diameter, coefficient of friction, etc., etc.) will have the greatest penetration, end of report.

RE: Who said that physics wasn't fun?
 

I always thought velocity was scalar and momentum was a vector(?).

To further mess with your mind, not only does the arrow have horizontal and vertical components to it's flight, but it's also spinning, which adds arotational vector. It's also oscillating for a good part of it's initial flight.

Passthru,every percentage point that we can shave off the wound loss ratio is one less piece of ammo for the animal rights folks. Don't you agree?

Now, to paraphrase your comment, I could give a rip what you use to hunt with since you seem to be experienced and knowledgeable. But, if you'd have bothered to read my entire post you would have noticed that I'm not talking about people that know what they're doing. I'm talking about the hordes of people who know diddly squat about bows and arrows, who never have walked into a pro shop or even know such things exist, don't know how to tune a bow or even how to properly select arrows and broadheads for that $50 POS compound they bought at the flea market. They're taking that junk out huntingand most of them are not doing the bowhunting community any favors. Extra arrow weight could very well make a difference for THEM.

In fact, if they shoot super light arrows froma 20-30 year-old bow with steel cables and teardrop connectors, rated for arrows at 6grains per pound minimum WHEN IT WAS NEW,they are at great risk for a trip to the emergency room.

Would it hurt you, personally, to accept a 400 grain minimum if it'd help keep one of those ignorant people from getting sliced and diced by a busted cable? If it'd keep just one of them from getting their teeth knocked out by a broken riser?If it'd help keep even one deer from being wounded and lost?Prevent one more storyfrom makingthe local evening news where some animal rights wacko wound up with a wounded deer on his front porch? If it'd prevent just one more black eye for bowhunting?

Frankly, I'm really compromising my beliefs a great dealby not calling for 450 or 500 grains. It's only in deferrence to the light arrow addicts that I am willing to acceptas low as 400 grains.

Put your own prejudices aside, look at the big pictureand think this thing through. See if I'm not talking at least SOME sense.

RE: Who said that physics wasn't fun?
 

Tfox, that's the best part of using heavy tips, it becomes relatively simple to match spine on a wide variety of arrows. For example, a full length Goldtip 3555 with 200-250 grains on the tip can be made weak enough to shoot at many low draw weights. If that isn't weak enough, you can add tip weight. You can do the same thing with aluminums.

And yes, I've built arrows like this for kids. They can be made to fly very well. A little bareshaft tuning will get you into the proper spine range quite easily. Unless they have somewhere around 23-25 inches of draw length and at least 35 lbs of draw weight, hunting big game is not a totally sure thing with any setup. However, the lower their draw weight and draw length, the more important the heavy weight arrow becomes.

RE: Who said that physics wasn't fun?
 

Arthur, in my opinon you're fighting an uphill battle here. I frequently get into discussions at the local archery shop, about all the benefits of the heavy arrows and 90% of these guys stare at me like I just told them the state banned bowhunting with anything less than 6 lb arrows. These guys would think that to get to 500 grains, you'd have to dip the arrows in lead. I think part of the problem is the number 500 - they must think it equates to pounds or something similar. They don't have a clue that there are 15.4 grains in a gram and that there are 28.3 grams in an ounce.

If states made new laws that stated arrows had to be no less than one ounce in weight, they'd probably not resist it as much. Imagine, archery might become less like shooting a gun and more like, well you know - shooting a bow and arrow. :D

RE: Who said that physics wasn't fun?
 

Arthur, momentum is a vector quantity as it is the sum of two vector quantities (the product mass and the respective vertical and horizontal components of the velocity vector). Speed, on the other hand is also a scalar quantity.Differientating speed and velocity seems to besplitting hairs sincespeed is distance over time and so is velocity.But speed does not imply direction whereas velocity does, making velocity a vector quantity too (along with momentum).

But then again, as you mentioned,throw in the angular momentum of the spinning arrow and it's oscillations, andthe physics of the gamestart to get complicated!

RE: Who said that physics wasn't fun?
 

Straightarrow, check this out. Here in good ol' Idaho, the requirement for arrow mass, was just reduced from 400 grains to 350 grains!! Ouch!