Impact formula

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School me in the math of inertia.I lay 1 LB on the head of a nail nothing happens. If I swing a 1 LB hammer at a high rate of speed taking advantage of leverage to speed its travel I can effectively drive it with a few blows.A 180 grain bullet hits a gallon of paint at 500 FPS, it might not even leak. If it hits at 2000FPS, the can explodes. The Karate black belt smashes cement blocks with his bare hands, Or I can swing a short 2x6, hit it on a rock and break it in half.Old time wood splitters slammed the block at speed making them more effective at both splitting wood, and removing human limbs.  How is this calculated?An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:Oh Boy,Willie, I'm poppin' up some popcorn for this!!  Sorry, I'm no help for you. I'm sure an Einstein or two will come along.MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Great question and I've always wondered myself.  I believe the force also has to be quantified in area applied, basically psi which would factor in hardness/surface at area of impact.  I've also wondered what effect - if any -  change of velocity at the time of impact has, ie would two identical blows except one is in the process of deceleration and one accelerating at impact at the same velocity strike with the same force?Last edited by SlowBlues; 06-02-2019 at 04:44 PM.
Reply:Hopefully somebody gives you the answer in english terms.... cause metric is just really gonna twist ya'
Reply:E= 1/2 m v^2.  Edit to add "A 180 grain bullet hits a gallon of paint at 500 FPS, it might not even leak. If it hits at 2000FPS, the can explodes. "       Going from 500 FPS to 2000 FPS raises the velocity 4 fold but raises the energy 16 fold because of the V^2.Last edited by FlaJoe; 06-02-2019 at 05:04 PM.
Reply:Simple enough, thanks   Strike THROUGH your opponent, right?
Reply:"would two identical blows except one is in the process of deceleration and one accelerating at impact at the same velocity strike with the same force?"    Yes, according to the laws of physics they would strike with the same energy.  HOWEVER, for them to be accelerating or decelerating then there much be forces apply to them ( however from opposite directions) so depending on what is causing those forces they could add or subtract from the energy of the impact.    For example, your arm applying force to the hammer to swing it would also add energy to the impact when the hammer hits the nail.
Reply:Originally Posted by FlaJoeE= 1/2 m v^2.  Edit to add "A 180 grain bullet hits a gallon of paint at 500 FPS, it might not even leak. If it hits at 2000FPS, the can explodes. "       Going from 500 FPS to 2000 FPS raises the velocity 4 fold but raises the energy 16 fold because of the V^2.
Reply:F=maWhere F = forcem=massa= accelerationYou can increase force by increasing mass or acceleration. The pressure formula should also be looked at but I'm not sure I remember it at the moment. I think it's Pressure=force divided by area but you should verify.
Reply:I see doubling the weight, doubles the energy. Doubling the speed quadruples the energy. http://www.1728.org/energy.htm"The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Originally Posted by SandyI see doubling the weight, doubles the energy. Doubling the speed quadruples the energy. http://www.1728.org/energy.htm
Reply:Willie B Originally Posted by Willie BSchool me in the math of inertia.I lay 1 LB on the head of a nail nothing happens . . .A 180 grain bullet hits a gallon of paint . . .The Karate black belt smashes cement blocks with his bare . . .Old time wood splitters slammed the block at speed making . . . How is this calculated?
Reply:Short answer...In classical mechanics, kinetic energy (KE) is equal to half of an object's mass (1/2*m) multiplied by the velocity squared. For example, if a an object with a mass of 10 kg (m = 10 kg) is moving at a velocity of 5 meters per second (v = 5 m/s), the kinetic energy is equal to 125 Joules, or (1/2 * 10 kg) * 5 m/s2.Inertia is an intrinsic characteristic of the object related to its mass. Inertia tells you how much force it will take to cause a particular acceleration on the object. Momentum is a function of an object's mass and velocity. Momentum is a measure of the kinetic energy of the object.Last edited by Fast Leroy; 06-03-2019 at 09:53 AM.Owner of Fast Leroy's Bar and GrillLiquor up Front, Poker in the Rear
Reply:Willie,Opus is correct, in that those 4 scenarios incorporate different kinematic calculations, and also involve engineering principles (regarding stresses/deflections/fractures) all at the same time.  There is no "this", in your question as to "how is this calculated", as they are distinct enough to need their own systems of solutions.  You would need several courses in physics and mechanical engineering to properly understand it all, and by "understand" I mean being able to set-up all the equations of motion and stresses/moments all completely on your own and solving them for the needed quantities.  Pick up a (hefty) university-level physics book, and if you can solve all of the kinematic problems in it, you are well on your way to understanding the systems you described. 1st on WeldingWeb to have a scrolling sig! HTP Invertig 400HTP Invertig 221HTP ProPulse 300HTP ProPulse 200 x2HTP ProPulse 220MTSHTP Inverarc 200TLP HTP Microcut 875SC
Reply:I am overwhelmed, stupefied. I imagined it could be reduced to pounds. V is not a concept I grasp. Been through Algebra I, II. With help from a couple of my sisters friends who were charitable, then a pact with a gay teacher who hated me (mutual), I passed.  I apologize for the question. It was, and is, over my head. No, I don't hate gays. I did hate that teacher. His being gay, (flamboyantly gay), was a quick, easy explanation C. 1972.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:Originally Posted by SandyI see doubling the weight, doubles the energy. Doubling the speed quadruples the energy.
Reply:Where is Jackie Chan when we need him ?If you let me score the block a little I'll snap it for you.Even with my forehead. I promise I wont wear lipstick.
Reply:and to mess it up more why can a 16 lb sledge move a pin that a 20 ton press will not budgeDo not argue with an idiot. He will drag you down to his level and beat you with experience.
Reply:Originally Posted by Fast LeroyShort answer...In classical mechanics, kinetic energy (KE) is equal to half of an object's mass (1/2*m) multiplied by the velocity squared. For example, if a an object with a mass of 10 kg (m = 10 kg) is moving at a velocity of 5 meters per second (v = 5 m/s), the kinetic energy is equal to 125 Joules, or (1/2 * 10 kg) * 5 m/s2.Inertia is an intrinsic characteristic of the object related to its mass. Inertia tells you how much force it will take to cause a particular acceleration on the object. Momentum is a function of an object's mass and velocity. Momentum is a measure of the kinetic energy of the object.
Reply:Originally Posted by Fast LeroyShort answer...In classical mechanics, kinetic energy (KE) is equal to half of an object's mass (1/2*m) multiplied by the velocity squared. For example, if a an object with a mass of 10 kg (m = 10 kg) is moving at a velocity of 5 meters per second (v = 5 m/s), the kinetic energy is equal to 125 Joules, or (1/2 * 10 kg) * 5 m/s2.Inertia is an intrinsic characteristic of the object related to its mass. Inertia tells you how much force it will take to cause a particular acceleration on the object. Momentum is a function of an object's mass and velocity. Momentum is a measure of the kinetic energy of the object.
Reply:Originally Posted by farmersammmYeah, that was my first thought.Let's say...you drop an 8lb artillery shell on your foot...might break a toe.  But that same shell travelling at 1100fps will go through a concrete wall.  In simple terms that I can grasp....the energy you impart to the object during acceleration carries thru to the point of impact  That initial energy has to be dissipated by the other object the shell strikes....causing great harm.  Shell still only weighs 8lbs, but it's packin' the thousands of psi it took to get it moving out of that gun barrel.In a perfect cartoon world, the shell would run out of energy, and at the terminus, drop on yer foot, and break a toe.  Still 8lbs worth of damage, but to a lesser degree.Or somethin' like that
Reply:Originally Posted by Willie BYou could teach physics in my son's high school.At a parent conference the teacher (a burly, biker type) described her frustration with my son. She presented this scenario:A hunter wants to shoot a monkey hanging from a tree 100 yards away. He knows that the monkey will release its grasp at exactly the same time the bullet leaves the barrel of the rifle. Where does he need to aim? Zack answered: a bit lower than he wants to hit, the monkey will fall that far in the brief time the bullet takes to travel. Teacher assured him he was wrong. The bullet will fall at the same rate as the monkey.  Aim at his heart.Zack tried to explain that the bore, and scope are not parallel. The barrel is deliberately pointed up in relation to the scope to compensate for gravity's effect on the bullet. Teacher dismissed that as ridiculous, "Nobody would do that"I was trying to pound it into this woman's head the student was right, book, and teacher were wrong. Mrs. B was getting upset, so I dropped the subject, and let this sanctimonious B**** go on thinking she was right.
Reply:Originally Posted by InsanerideBoth are rite in different ways: the bullet is still effected by gravity (32ft/second^2) so is the monkey so they will drop at the same rate. Kentucky windage compensates for Gravity and adjusts the barrel angle so that a stationary target not effected by gravity can be hit by the bullet that is effected by gravity. This scenario has been known since before I was born.
Reply:Willie, mammoths don't fall from trees, they move horizontally. Your sons physics teacher was explaining gravity. Windage accounts for gravity provided you know the range.  Your son saying that you lead the moving target applies to a target moving horizontally at hi speed. A bullet traveling at 2000fps is way faster than monkey falling at 32fps^2 . If the monkey is only 500 feet away from shooter then the bullet should only take 250 milliseconds to reach the monkey. The monkey barely moved at all but is falling at the same rate the bullet falls.I first heard that problem forty years ago but no monkeys falling, different approach .Which travels faster, a .22 or 45 caliber? The twenty two of course, that's why the twenty two travels further. They both hit the ground at the same time provided they were shot at the same time from same height and barrels level.Gravity is a weak but constant force. I forget what the speed needed for a rocket to escape Earths gravity is but, the faster a bullet travels, the farther it travels.Btw, a cavemans spear would travel faster than a rock so the Force would be more than a rocks and also has more pressure.Force equals mass times acceleration . Pressure equals Force divided by Area.Last edited by Insaneride; 06-07-2019 at 01:23 PM.
Reply:Willie, I stand corrected if my math is correct. In 250 milli seconds, an object or monkey wall fall 2 feet based on the speed of gravity. Gravity on Earth is 32ft/second squared. In a quarter second or 250 milli seconds the equation becomes32ft per 0.250seconds squared.32ft per 0.0625 = 2 feet.  So, depending on the size of monkey, aim for his scrotum if you want a heart shot provided windage is set correctly for intended range.In my defense, that problem was posed differently when I first heard it. It didn't include monkeys the way I heard it.At 100 yards a bullet will rise somewhat due to correcting the sight. If sighted for 100 yards, the bullet will rise above the line of sight. By correcting for gravity, the bullet will not fall in a short range. The monkey will. Personally I doubt I'd choose to shoot the monkey anyway.I don't think I used the term "lead". I suggested anticipating where the monkey will be, aim there.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:A bullet won't start it's decent untill it has finished it ascent, which is distance which takes time. In a short period of time it can travel and fair distance. Basically a fired bullet won't start its decent untill it has hit the monkey which is falling or traveled quite some distance."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Lets get back to breaking blocks and boards and black belts and stuff.I'm an ol man but maybe the docs in the ER can give some insight when they roll the stretcher in with part of the door still attached to yer head.I did enjoy the swinging a one lb hammer story. I figure these are in the 14 lb range.
Reply:Originally Posted by idacaland to mess it up more why can a 16 lb sledge move a pin that a 20 ton press will not budge
Reply:Willie, you gave a distance to monkey of 100 yards (300 feet) and speed of bullet from your first post of 2000fps. At that speed it takes 150 milli seconds for bullet to hit monkey. If the monkey lets go at the exact time bullet is fired then the monkey will fall only 8.6 inches. You didn't say how big the monkey is but 8.6inches below his heart should give you a heart shot.You didn't use the term lead or Kentucky windage but adjusting or "anticipating" is leading or Kentucky windage imo.Sandy, this old physics exercise was assuming a perfect world, level barrel, no air resistance or wind. Gravity, force and motion were the intended point to help Willie understand impact formula. He said its way over his head tho so there's no use trying any further, besides, he's adding trees and monkeys into the equation that makes it even more difficult to help him.How I was explained: at the same time one bullet is fired from a level barrel, a second is dropped from the same elevation. Both fall at the same speed and would hit the ground at same time. The fired bullet does not rise above the horizon but the horizon does fall due to curvature of the Earth. If the Earth was flat, they would hit the ground at the same time but because horizon drops, the fired bullet has more distance to hit ground than the bullet with no horizontal vector. Quote from a physics book, " many people including hunters seem to have initial difficulty in believing." The picture shows a bullet fired and casing ejected land on the ground at the same time. It's a study in gravity, a weak but constant force. Attached Images
Reply:Free fall is key here. There's a huge difference between a free fall and being propelled in some direction. Free Fall, free fall. Fire two shots at the same time, one straight up,,,,,,, one straight down. will both projectiles hit the ground at the same time ??Of course, if the bullet hits the monkey then I guess they both do hit the ground at the same time in a vague sort of way. Last edited by Sandy; 06-08-2019 at 11:36 AM."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:The physic book did say that many people don't get it but, a bullet fired with barrel level will hit at the same time that a bullet dropped from same elevation at same time. Being propelled in another direction does not escape gravity unless  traveling at 25,030 miles per hour. That is the escape velocity for Earths gravity.Again, from physics book: "this result leads to a most interesting situation, which many people, including hunters, seem to have difficulty in believing.""After hunters think about this situation, they soon remember that to counteract the gravitational pull on the bullet, the rear sight on a rifle is adjusted so that the rifle is actually aimed a small distance above the target."Some newer ACOG type rifle scopes use stadia or graduation marks to determine range to correct offset or Kentucky windage.Last edited by Insaneride; 06-08-2019 at 12:16 PM.Reason: Spelling
Reply:That's where the physicist is actually off. Hunters do get it, he doesn't. Hunters know full well how guns are "sighted in" and have no use for one that isn't sighted in. A firearm not sighted in is nothing more than a bang stick. No hunter will ever just fire a firearm with the barrel parallel to the ground. If a duck is high in the air, we 'aim' high in the air. We even take into account true ballistic distances (gravity distance) vs ground distance when shooting extreme uphill/down hill situations. Snipers even take the coriolis effect when shooting long distances. I doubt the physicist took that into account. Yes hunters and sportsmen do get it. The scenario was shoot the monkey, not fire a firearm parallel to the ground. We know how to hit the monkey.Last edited by Sandy; 06-08-2019 at 12:53 PM."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:The bullet fired, case ejected, thing is somewhat strange.The case falls at a speed that will eventually approach terminal velocity.  It takes time to reach terminal velocity.  A hail stone takes a bit to reach the 90ish mph before it hits yer noggin.  Drop the hail stone from 3 feet above your head...……….stand under a storm, and let a hail stone hit yer noggin...…...you'll get my driftSo, we got the case hitting the ground at a given time,  I can buy that.  But what gives me pause is the relationship between that short fall (albeit at less than terminal velocity), and the variable distance the bullet might travel.  Are ya sighting it at something 100yds, or something at 800yds.  There's gotta be a difference somewhere.  The only variable I can see is the sighting distance...…….the case will drop at a steady rate whatever distance the bullet strikes.Last edited by farmersammm; 06-08-2019 at 07:12 PM.
Reply:Far as the sledge hitting the pin.  I think it's sort of a matter of square inches.  Sledge is packing some force, and it's striking something that's very few square inches.  Force is concentrated in those few square inches, as opposed to the sledge striking something equal in area to the face of the sledge, which dissipates the force.
Reply:Back to the ejected case thing.I'm sure there's a curve showing the acceleration per distance of fall.  It's a constant.  Weight doesn't matter.  Bowling ball falls as fast as a marble.But the distance to the target is something wholly unrelated to the constant fall of the cartridge case.
Reply:Now, if you're talkin' about my earlier comment about the artillery shell falling straight down after it's exhausted its energy from the powder charge.Yeah, in the perfect cartoon world, it would reach terminal velocity at the same rate as the shell ya just dropped on yer foot.  It's reached zero acceleration,, and drops at a theoretical 90 degree angle to the trajectory.Science is the discipline of observing common phenomena, and trying to put numbers to it.  This allows folks to predict outcomes for any given situation, if the mathematical model is correct (something like an axiom that's been proven... yielding a rule)This involves statistics...………..how many times do ya get the same result within the acceptable realm of the bell curve.  There's no way to ACTUALLY 100% PROVE ANYTHING, IT'S ALL A MATTER OF REPEATABILITY GIVING SOME DEGREE OF ACCEPTANCE.  Ya don't have to hit yer thumb with a hammer more than a few times to verify that it ain't such a good thing to do  That's called "sampling".
Reply:Anybody stop to ask the monkey how he feels about all this?
Reply:Originally Posted by farmersammmBack to the ejected case thing.I'm sure there's a curve showing the acceleration per distance of fall.  It's a constant.  Weight doesn't matter.  Bowling ball falls as fast as a marble.But the distance to the target is something wholly unrelated to the constant fall of the cartridge case.
Reply:Yeah, I'm over simplifying.  I'm guilty of that.
Reply:Gordo...…...some ol' fat boy in the Southern Hemisphere, falls offa the tractor.Bob......some ol' fat boy from Nebraska (Northern Hemisphere), falls offa the tractor.Given the Coriolis Effect, climate change, and the variable winds...…….Which one's gonna hit the ground first?I'm thinkin' the only difference is the language the %^^%$%#$@#@#$% is gonna be.We could split hairs...……  https://www.introduction-to-physics....r-of-pisa.html  I'm an old science guy, so I stick with the Pizza Theory
Reply:But...…..I'm all in for things Pizza!!!!!!!!!!!!!!!!!!!!!!!!!
Reply:Originally Posted by SandyIn a vacuum weight doesn't matter. In our atmosphere many things matter, wind resistance being the primary factor most of the time. That's why different objects have differing terminal velocities. What can be said in general terms in the earths atmosphere is that items of similar size and weight (mass and volume) will accelerate and fall at a very similar rate. Visually imperceptible most if the time. A lead dart will obviously out run a sheet of paper in a free fall race. The sheet of paper may take a long time to reach the ground from 10,000 feet, a lead dart not so much. The problem is when we take a simple classroom science demonstration, designed to convey a concept, and turn it into an absolute with no variances for anything.
Reply:Sammy, pointing at flying monkeys above with your 8 pound round or whatever you said will still be drawn to Earth at a rate of 32feet per second squared. No exceptions not even speed. You will get more distance firing above your target but gravity will still be constant.Even if the monkey in the tree is at say a fifteen degree angle above the shooter, the bullet will still be drawn to Earth at a rate of 32ft/second^2. The bullet at Willies specs of 2000fps and range of monkey of 300 feet takes 0.150 seconds to hit the monkey. In that time, the monkey and bullet falls 8.6 inches. If Willies son aims below the monkey, he's gonna miss. Any questions?Last edited by Insaneride; 06-08-2019 at 11:40 PM.
Reply:Originally Posted by InsanerideSandy, you were just starting to get close to understanding that a hunter aims above a target to adjust for gravity, then you had to throw duck vectors in.
Reply:Yes
Reply:And no, a vacuum doesn't meen weightless.
Reply:Sandy, I still can't grasp the belief that the entire universe is infinite, I just except it and move on. Hope that helps.And if it is the entire universe then how is it infiniteLast edited by Insaneride; 06-08-2019 at 11:50 PM.
Reply:Ok Sandy, say a sniper shoots a sitting bad monkey at 500 feet away using a 2000 fps round. It will take 1/4 second to reach the monkey, in that time, the bullet falls two feet, the sniper aims or adjusts for two feet above the monkey. Any questions?Oh and the monkey is uphill at 20 30 or even fifty degrees above sniper, doesn't matter, bullet is drawn to earth by gravity at a rate of 32/second squared. I hope that helps because my work is done here.Last edited by Insaneride; 06-08-2019 at 11:58 PM.
Reply:Actually angle of elevation does matter  because now gravity is also helping slow the bullets forward velocity  and if the monkey is just sitting there I think it's just asking to get shot.