Velocity of Arrow Vs Speed of Sound
 

Another post got me to thinking:
An arrow travelling at 270 feet per second at 60 feet takes approximately 1/5th of a second to get to the target. Sound travels at the speed of 1129 feet per second. It takes 1/20th of a second to reach the target. So if you shoot at a deer at 20 yards it has 3/20ths of a second to react.

At 30 yards, the arrow takes 1/3rd of a second to get to the target and the sound takes 2/25ths of a second to get there giving the deer at 30 yards 19/75ths of a second to react.

At 40 yards, the arrow takes 11/25ths of a second to get to the target and the sound takes 1/10th of a second to get there giving the deer about 1/3rd of a second to react.

So the longer the shot, less time to react. Even though I'm talking a fraction of a second, I always see the buck duck when the shot is taken. I just think its amazing how fast they react to a single sound when I know no human being could react the same way. I guess it comes from living their whole life always on guard for predators.

I know the preceeding information was pretty much useless to anyone, but once again I was over analyzing.

RE: Velocity of Arrow Vs Speed of Sound
 

How do you know how fast the arrow is traveling when it gets to the yardages you cite?

RE: Velocity of Arrow Vs Speed of Sound
 

Thanks for crunching the numbers for me. Always wanted to do the math.

RE: Velocity of Arrow Vs Speed of Sound
 

that is pretty cool ive always wanted to figure that out but never really did it. thanks lol
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RE: Velocity of Arrow Vs Speed of Sound
 

A deer walking slowly and steadily at 2mph at 40 yards can move 1 foot in 1/3 second. Just think how much he can drop within 1/3 seconds. :D

RE: Velocity of Arrow Vs Speed of Sound
 

I know the point you are trying to get to AF, but GMMAT has a valid point here. I do remember a video I seen once that showed a miss on a deer. They drew a yellow line on the deer that cut the body in half. The shot was 23 yards. The arrow passed thru the yellow line, but over the back of the deer. It is amazing how quick their reactions are. Now, put a deer on edge and they will react to the snap of the string even quicker. I always laugh when I hear people say they are shooting too fast for a deer to jump the string, man their arrows must be blazing.

RE: Velocity of Arrow Vs Speed of Sound
 

The arrow leaving a bow at 270 feet per second will slow down the further from the bow it gets, but when you are speaking of fractions of a second, I don't believe the drop in speed will be that measurable for the average person. For every arrow weight the terminal velocity and then the rate of decent would be different.

All I was saying after doing the math was that is FAST for a deer to hear the sound of the bow shot and react.

RE: Velocity of Arrow Vs Speed of Sound
 

The point is......a chrono'd 270fps is about 2' in front of the bow.

Put the chrono now at 20yds and measure that speed.

Put it at 30yds and do the same.

Put it at 40yds and do the same.

NOW crunch THOSE numbers.;)

I ask these questions to find out for myself if the below IS true.....

You ARE speaking in fractions of a second in regards to reaction time.

RE: Velocity of Arrow Vs Speed of Sound
 

Well, if we could all get a bow that shot at 1140 fps, the deer would be hit before he heard the shot, or it would be simlutaneous if the arrow slowed down 11 fps in the distance shot. Now all we have to do is all start doing upper body strengthening excercises and lots of them.

RE: Velocity of Arrow Vs Speed of Sound
 

I'll let you know this year because I've got my Drenalin shooting right at 1140 f.p.s.....:D

RE: Velocity of Arrow Vs Speed of Sound
 

AF...i did something similar once...but was comparing bow speeds and time it takes...

reallllllly not all that different from most of the bow speeds out there...so i kinda chuckle when i hear guys say shoot a faster bow to avoid the "duck"

cant remember the numbers and have no desire to do the crunching again...it just dont make a difference with the reaction time they have...

i think too many guys shoot alert deer or make deer alert by trying to stop them for the shot....

RE: Velocity of Arrow Vs Speed of Sound
 

Mauser, I'm not even considering trying to find a way to avoid the duck, just saying at those speeds it's amazing how quickly the deer react to the "whump" of an arrow being sent down range. I am in total awe of that quick of reaction speed.

RE: Velocity of Arrow Vs Speed of Sound
 

A while back I did some similar calculations. I arbitrarily chose the horizontal deceleration of the arrow to be 0.25 ft/s per yard travelled. And I dragged my calcs out to 50 yds, at which it takes an arrow starting at 300 fps, .51 sec to get there.
The speed of sound is 1116 ft/s. It takes .134 sec to go 50 yds. Difference in time is .376.
At 30 yds an arrow takes .294 sec & sound takes .08 sec. Difference of .214 sec.

A deer does not have less time to react the farther away it is.

RE: Velocity of Arrow Vs Speed of Sound
 

Which is why I wanted the "real" numbers.

Thanks, Rybo.

RE: Velocity of Arrow Vs Speed of Sound
 

I'm confused.....How can the deer have less time to react on a further shot? At 20 yards, you state it has 3/20 of a second to react.....That's far less time that the 1/3 of a second at 40 yards, isn't it? Or have I completely misread this?

RE: Velocity of Arrow Vs Speed of Sound
 

Here are some numbers(speeds @ different yardages)that I pulled from a Kanga post in the Tech forum.

mobow, you're right 3/20th of a sec is less than 1/3 sec. Think of it in percent. 3/20th is 15% of a second. 1/3 is 33% of a second.

I'm sure AF's brain was hurting after calculating all that. It is interesting though and yes those suckers react fast.

RE: Velocity of Arrow Vs Speed of Sound
 

My bad, using your arbitrary deceleration ratio, there is a 5/100ths difference using the initial speeds I used. I concede that the arrow will slow down, but even at that distance its the difference is very miniscule. Now take into affect the sound level difference. Something that is 50 decibels at source is not going to be as audible at 50 yards. Is the softer sound going to startle an animal as much as the lounder one?

RE: Velocity of Arrow Vs Speed of Sound
 

I don’t know what the loss of decibels over distance is, but yea it is pretty common that a loud noise close, will incite more reaction that a dull noise from farther away.

I was only number crunching for the situation that if the sound was audible and an animal was going to react, it had more time to do so from further out.

RE: Velocity of Arrow Vs Speed of Sound
 

I have seen deer appear to duck a shot from a muzzle loader with a bullet moving at 1800 fps, which is faster than the speed of sound. I personally have never had a deer duck a shot from a bow or a muzzle loader. I always hit right where I am aiming for, or within an inch or two.

I'm not going to say it never happens, but I bet most that say a deer ducked the shot probably miss judged the yardage or the deer was starting to move before they released the arrow. Basically they just missed.