Speed of sound question. Need to settle a debate.
 

A guy that I work with and I are having a little debate. He is saying that with an arrow flying at 310fps a deer will be less likely to jump the string than at let's say 280. I said that he's right in a sense. I'm saying that the "actual" time difference isn't that great to say that with 100% confidence. Does anyone know how to figure out how much time it takes for an arrow to hit a target at a given distance at any given speed? Is there an equation for such a thing?

Thanks

RE: Speed of sound question. Need to settle a debate.
 

I'm not a math man, so forgive me if I am wrong. But if speed stays constant at 300fps, it should travel 20yds in .2 seconds at 280 it would .214 seconds. Is this correct?

RE: Speed of sound question. Need to settle a debate.
 

Umm, you've got the formula! FPS = Feet / Seconds = Distance / Time.

At 310 fps it will take .1935 seconds to hit a target 20 yards(60 ft) away.

60/310=.1935 seconds

60/280=.2143 seconds

The speed of sound is approx. 761.21 miles per hour. Translated is equates 1116.44 fps.

The sound of your bow/arrow will reach the deer as follows:

60/1116.44=.0537 seconds

The speed of sound is roughly 3.60 times faster than the 310 fps arrow or 3.99 times faster than the 280 fps arrow. Now, all this is based on static numbers, but your velocities of your arrows will degrade over distance traveled....thus making all the above numbers completely irrelevant. But, the theory and premise are there for you.

RE: Speed of sound question. Need to settle a debate.
 

Jason,

You aren't by chance a rocket scientist are you? That's an awefull technically correct answer and in record time. I'm impressed:)

RE: Speed of sound question. Need to settle a debate.
 

Great! Thanks for the info. I have ammo in the reserves now. lol

RE: Speed of sound question. Need to settle a debate.
 

Nope, I am a mech. engineer though. I occaisionally have my brilliant days....today is one of those days....they don't come by very often.[&:] I actually impressed myself, usually when I explain something is doesn't come out of my mouth or onto the screen anything at all like it's going on in my head....today it all came very fluidly!:D

RE: Speed of sound question. Need to settle a debate.
 

The pro at our local bow shop explained the whole thing to me once. His answer was similar to that of Jason N above but included deer reaction time and the speed at which a deer can drop and then leap. I wont attempt to get into the numbers.

Bottom line, no matter what speed your arrow is traveling, deer have plenty of time to jump the string if your bow is loud enough to alarm them.

RE: Speed of sound question. Need to settle a debate.
 

I did a similar calculation last year during gun season for a new bullet I was shooting.
12 gauge core loc'd copper solid sabot - something like 1350 fps.
Boiled down to: by the time the deer heard the shot the bullet was through him and x feet on the other side.

Now if I can only get my bow to shoot 1350fps[&:]

RE: Speed of sound question. Need to settle a debate.
 

I don't think it's so much the bow noise, but rather the arrow noise. As the arrow approaches it gets louder. So, some deer may jump to get out of the way. I often wonder how many times, the one that jumps out of the way, has heard that sound coming at them??

RE: Speed of sound question. Need to settle a debate.
 

Very interesting thought, Bees.
The arrow is certainly making noise in flight, especially if it is fletched with helical, shield-cut feathers, and the sound would radiate in all directions, including that of the deer.

After thinking about it for a few minutes though, it seems to me that the sound wave generated by the bowstring upon release would outrun the others since it occurred first, and it is moving over 3 times as fast as the arrow that is generating all subsequent noise.

I'll hurt my brain if I try to figure out wether the deer will hear all of the sound before the arrow strikes, but then again there is the issue of how fast the deer can react.

Having noted my own reactions to loud, unexpected noises in the past, I can attest that it only requires one instant to zero in on the source of it, not necessarily a continuous noise, if it is fairly close.

RE: Speed of sound question. Need to settle a debate.
 

I don't think string jumping is as much of an issue as people like to make it out to be. I think a lot of people like to use it as an excuse for just plain old missing, miss judging yardarge or pulling a shot.

The newer bows are plenty fast and quiet enough that it shouldn't be an issue. Bottom line is learn deer body language and don't shoot at alert deer. If you shoot a relaxed deer that isn't looking right at you the chances are really high the arrow will be in the dirt on the other side of the deer before it knows what happened. I find it hard to believe that a deer can hear something, react and be out of the way in a blink of an eye.

I don't remember where I read it, but some engineer or something did the math. In order for a deer to really jump the string after you shoot it's feet would have to leave the ground while it was going down, or be attached to the ground. It was physically impossible for it to move that fast in a downward motion and stay planted. It defies the laws of gravity.

I however have seen the video of them moving on the shot. These critters are amazingly weary and fast.

I don't believe the speed differences you are talking about would make any difference at all to the deer. They would help with the yardage however. You could be a bit off on your estimation and hit closer to your mark than with a slower bow.

Paul

RE: Speed of sound question. Need to settle a debate.
 

I've seen a few string jumpers on hunting shows - most of the time the shots are 50yards plus - plenty enough time for an animal with good hearing to react - including humans IMO.

RE: Speed of sound question. Need to settle a debate.
 

I too think string jump is highly over rated. I've had one deer duck my arrow in 15 yrs of bowhunting. That old do was 20yds, facing straight on and watched me draw, I realeased and she ducked to the left and that arrow wizzed right on by.

Yes, it was a stupid shot, I was 13 and had only been hunting a few times with bow in hand.

RE: Speed of sound question. Need to settle a debate.
 

When I first started Archery hunting.....about 4 years ago, I had a doe bust me...I was sitting at the base of a tree and she snuck up behind me...anyways, she ran off then turned around and started coming around the other side of the tree...the tree was huge, so she couldn't see me, so I pulled by bow back and waited for her to come around the other side, she finally came around and was only about 10yds. away, I released and in less than a second I watched her as she jumped straight up and I seen the arrow pass under her chest and into the ground as she ran off....I was completely amazed. It was my first year bowhunting, I was around 19 or 20 yrs. old and I didn't have any silencers or anything on my bow and it was pretty loud and it only shot about 180-200fps. That was the only time that happened but I couldn't believe a deer was able to jump out of the way at 10yds. Oh well, I've learned alot since then, lol.

RE: Speed of sound question. Need to settle a debate.
 

Bowhunting October Whitetails. Find it. Watch it. At 20 yds they go slow motion. They superimpose a white line on the deer's belly. You hear the shot, the deer instantly starts to crouch. When the arrow reaches the deer, the white line is up on it's back as the arrow sails harmlessly over the top. Very impressive. Now I have to watch it again. :)

RE: Speed of sound question. Need to settle a debate.
 

Someone once calculated that a bow would have to shoot faster than 700 feet per second before a deer couldn't get out of the way in time.

I've never had one jump. but then again, they didn't get a chance to hear that sound again.

I still wonder if the ones that do jump or duck, have been shot at before and they know that noise ain't good. :eek:

RE: Speed of sound question. Need to settle a debate.
 

I really think it all boils down to if the deer is in a state of relaxation or is very alert, JMO.

RE: Speed of sound question. Need to settle a debate.
 

Jt has the answer, relaxed deer don`t jump the string. Deer that are alert and looking for danger can and do jump the string. If it was the noise from the bow that causes them to jump the string than no one shooting a crossbow would ever kill a deer. It always amazes me just how fast a deer can react.

RE: Speed of sound question. Need to settle a debate.
 

You can prevent the string jump if you place two large balls of cotton in the buck's ears prior to the shot. Of course, you'll have to be able to move faster than the speed of light, but if you can, you eliminate the problem of arrow speeds that are below the speed of sound.

E=mc2/light speed*3/kinetic energy of cotton ball placement/your age x your weight.

RE: Speed of sound question. Need to settle a debate.
 

I just read an article on this subject. The writer said something like,....you need to aim about 17 inches low on a whitetail that is 30 yards away. Someone please tell me this is NOT accurate. I know that a deer will drop some, but 17 inches before the arrow hits! This just sounds a little extreme!

I don't have the experience yet, so I cannot dispute this. Does anyone actually aim below the deer's body??? If this is accurate, that has got to be one hell of a mental game.