With Sheila, my new Matrix 380, I wondered about how much string-jump could be a factor as compared to my vertical bow. Most discussions on the subject reference either string-jump due to the sound of the bow or due to movement of the bow. Most don’t discuss both and I haven’t seen any good discussion that factor in the speed of sound. So, I figured I’d do a little calculating. But before I could begin, I needed some hard facts. For instance, what is an average deer’s reaction time in seconds? I could find a pretty good number for humans but not deer. It’s about 0.16 seconds for humans. That’s the time it takes for you to recognize a stimulus and move your hand because of it. In school you probably did a little physics experiment catching a falling ruler and figuring out your reaction time based on the number of inches the ruler fell. Part of reaction time has to do with nerve conduction speed and distance. Since nerve conduction speed in mammals is pretty similar, small mammals would generally have faster reaction times than larger animals (although larger diameter nerves have faster conduction speeds). It should follow that: Since the distance of a human being’s brain to hand is probably about a third longer than the distance from a deer’s brain to the muscles in their front shoulder, a deer’s reaction time could be about 0.11 seconds. That’s my first assumption, not a hard fact. (If anyone has real data, I’d like to hear about it.) My second assumption is that the speed of sound is about 1,116 feet per second. That’s at standard temperature and pressure. The number changes with differences in each. My third assumption is that the acceleration due to gravity is 32.174 feet per second squared. Depending where you are on earth, that number changes a tiny bit too. All of these assumptions, except maybe a deer’s reaction time, should be more than close enough for government work. The calculations aren’t easy to show on the forum, so I’ve put them in an Excel spreadsheet and made them available here:
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https://dl.dropboxusercontent.com/u/14080410/StringJumpCalc.xlsxI’m wondering whether the numbers generated by the spreadsheet seem to correlate with what you’ve all seen with your bows. I’d also appreciate it if you would punch holes in any of my assertions and, if you’re so inclined, check my math. If the assertions and calculations are right, the spreadsheet could be useful to quell curiosity. Please let me know what you think.
. It's difficult to tell where the arrow hit and at what angle. What was the distance to the deer and speed of your arrow?