Physicist: There’s a cute trick you can use here. It a falling object starts at rest and ends at rest, then it gains all of its energy from gravity, and all of that energy is deposited in your unfortunate foot.
Kinetic energy is (average) force times distance; whether you’re winding a spring, starting a fire (with friction), firing projectiles, or crushing your foot. The energy the object gains when falling is equal to its weight (the force of gravity) times the distance it falls. The energy the object uses to bust metatarsals is equal to the distance it takes for it to come to a stop times the force that does that stopping. S0, 
The distance times the force that gets an object moving is equal to the distance times the force that brings that object to a halt.
Of course, the distance over which the object slows down is much smaller than the distance over which it sped up. As a result, the stopping force required is proportionately larger. This is one of the reasons why physicists flinch so much during unrealistic action movies (that, and loud noises make us skittish). Something falling on your foot stops in about half a cm or a quarter inch, what with skin and bones that flex a little. Give or take.
Bowling balls: keeping podiatrists gainfully employed for 700 years.
So, if you drop a 10 pound ball 4 feet (48 inches), and it stops in a quarter inch, then the force at the bottom of the fall is 
The bowling ball picture is from here.
I think you meant 4000 lbs not 400. In fact 10(48/.125)=3840.
How do I metric system?
@Karl
There’s a subtlety there I was worried would distract from the point. “Pounds” are a measure of force, so they fit very naturally. “Kilograms” are a measure of mass, so when you talk about “weighing” a certain number of kg what you really mean is “the force experienced by X kg in Earth’s surface gravity”. X kg experiences 9.8X Newtons of force (9.8 meters per second squared is the acceleration of Earth’s gravity).
However! If you just ignore all of that and think of kg as just being the weight of an object (instead of its mass), then everything works out in basically the same way. Nobody measures in Newtons anyway (for reference, 1000 N ≈ 225 Lbs).
I broke my foot dropping a 10 pound bowling ball on my foot. So wtf are you guys Saying?
May I know how to calculate if a polycarbonate sheet rated to take 2 kg weight dropped from 1.5 meters can withstand a falling bullet exerting what is rated at 30 lb-ft impact force?
My calculation from your D*W above says that the sheet can withstand about 22 lb-ft force, is this correct or am I missing something? I have no data on the “bounce” or travel of the sheet surface, i just know that the sheet takes that load dropped from that height.
Many thanks
Well Raine it depends on how tall you are do properly determine how much pressure slammed onto your foot.
I am looking for the answer to this question:
What is the impact of an 18 pound object falling, 12 inches, onto a 50 pound child who is 4’3″ tall?
My friend dropped a stationary mortcycle wieging 700 punds by the owners manual . and well its swolen he can barley walk on it 1st day in from a tipsy last night lol its swolen middle of foot is where impact was but his toes are to ? Size 12 shoe …. Were gna just give it another 2 days or shld we make a splint
how about 50 lbs of potatoes on top of your head? my neck and head were not strong enough to stop it though. Free fall about 8 feet
Scenario: I have a 700 lb motorcycle which was blown over by the wind. The motorcycle was previous leaning at about a 50 degree angle and was toppled in the opposite direction . This meant that it first had to blown past 90 degrees and then past the 90 degree tipping point.
My first question is how much wind would it take to move 700 lb object? My second question is how much weight would have to be put on the opposite side in order to stabilize the motorcycle and prevent it from being blown over? The only part that may be difficult to compensate for is that the motorcycle had a cover on it which may have acted like a sail.
I flew off top a ladder from 35 feet on to my face on an asphalt curb infront of the home owner 20 feer away.And I was 225 lbs with 15 lbs of climbing gear on.Whats my impact.Or gforce if you may..
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Please help me I’m very worried about my 37 year old son he was on the rocks next to the pier fe sliped on seaweed while walking modertly fast feet flew out from under him his body was paralell to the large.flat rocks he landed on the back of his head first main brunt of impact on about a area the size of a 50 cent coin. He was knocked out does not know how long some guys helped him up walked him to his car like an idiot he drove home. He called and I told him I live 1200 miles from him if he didnt go to emergency I would call 911 in his area for a ambulance so he went dr said severe concussion no brain bleed or swelling set him home said if head hurts In morn back to hospital..what I want to know is how hard his head heat that 6″ thick rock.force of impact.i can do it but im so upset I cant think straight.
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ok so I have a 50 lb object falling one foot. that equals 50 ft lbs. if it is now at 3 feet, how many foot pounds is it? or do I just multiply by three.
Ok, now the real question. The Undertaker choke slams Mankind on top of the hell in a cell cage. The force was enough to break through the fencing of the cage causing him to fall the remainder of the distance onto the mat. How much force was there when he hit the fence, and how much on the ground. Let’s guess that Mankind was 300 lbs. and the chokeslam was a fall from about 4 ft. to the fence. The cage was another 16 ft roughly? Help me out here.. How is this man alive?
I had a 24lb steel hitch drop onto my bare head from a height of 10ft. How much force did I experience?
Gave me a concussion, but I’m wondering how much trauma may be undetected.
A 44.5 lb. microwave slid down a 9 step ladder that stood at approximately 11 feet high ( top of the rails), the microwave didn’t free fall, but, slid down the rails at a diagonal angle of 60 degrees and hit me in the face. The lowest point of the rails was approximately 4 feet.
I am trying to figure out which rating do I need for a bullet proof vest: Knife Resistant Level 1 or Knife Resistant Level 2 . here are the energy (joules) ratings: Energy (joules) 24 36 33 50.
How do I determine which rating I need?
I know 17.7 foot-pounds = ~24 Joules, but what is that in real world physical examples?
Thanks
Paul
I fell 9 feet with a collapsing stairway, landed on the now pointed upward unfinished steps, which then contacted approximately 6 square inches of my 250 lb body.
I weigh 360 pounds and am 6’2″ tall. Walking on concrete my feet slipped out from under me and my butt being 3 feet from the ground slammed into the concrete. How much weight is that like? A week later I fell again only I went up about half a foot before crashing down to concrete. A total fall of 42 inches of 360 pounds. How much weight is that like?
Need this info to get my doctor to understand it was no small fall.
Thanks, Me no math wiz.
So if I’m dropping 9,5o0 lbs from 48″ and the pile goes down 2″ is
9500(48/2) correct?
Ok simple laymans terms. I want to build a power hammer it will have a 25 pound steel bar attached to the handle. It will drop from 24 inches to a stricking anvil. What is the force in pounds I can expect with each hit.
Tomorrow, I will be having a 200 pound woman stand on a chair 2 feet high and jumping on to my stomach. How much weight is that?
I broke my head trying to sort out these calculations in the imperial system (and I’m an American).
Physicist; It’s nice to have an equation to work with. However I have no way to express this because I do not know how to type a fraction. Look above and you will see my query.
Wanting to know how much force is exerted on my back from two falls.
My butt being half the distance of my height from the ground would be 36 inches. The weight of the object ( me ) 360 pounds. The ground is 36 inches away from the contact point on my body, my hips.
The surface I hit was nogive concrete. So you say above the stopping distance in your example is 0.25. Mine was 36 inches falling and immediate stop.
Less than a week later I fell on my lower back after slipping on loose gravel where my thrust was up first then down on concrete. I estimate 6 inches more on that fall so 42 inches with an immediate stop of 360 pounds.
I was just trying to estimate how much weight would it take to simulate that if I were lying on the ground? 360 pounds or would it be like more weight. OH well I guess there are just some equations even physicists can’t figure out.
Thanks anyway.
I had a 5 pound dewalt impact drill fall on my head fro approximately 10feet how much force did it create on my head
Ok so, I just had a pallet weighing 152lbs, with approx 90lbs worth of items on top, be let down from a height of 4 inches onto my big toe on my left foot only. I was wearing thin mesh shoes. It landed just below the joint connecting it to my foot. It hurt like nothing else and was stuck there for a good 10-15 seconds before I was able to get help.
That was 5 hours ago. There is a minor bruise with hardly any soreness. I’m walking fine and did so immediately after aswell. I can bend it too. According to What I have ready and the calculations I have done, that amount of weight, should have done something!
What’s up?
What I mean is, am I doing my math wrong? What actually happened to my toe?
I want to make a water wheel to create electricity I e 8 lb weight at 12 inch from centre and 4nft from centre and 8 ft from centre
On 2/21/18 working building commercial planes installing a trunion block that weighs 50 lbs laying on my back on a bench fell 3.0 ft from above my face free fall to my face but i survived from speedy actions of turning my head left but it still struck my right side ripping my ear to shreds and struck my head, collar bone and shoulder. What was the full amount of force that hit me? And what is the survival rate of this tool hitting me. The shape is a cylinder tube that was pointing down on me the rest is all steel . I do have pictures of it if someone would like to see my luck
I’m a powerlines,I had a 10lb hammer fall 24ft and hit me in the shoulder blade/back..how much force did the hammer have wjen it hit me…and yes I’m ok?just ALOT of bruising…lol tks
If an 8 oz piece of chain falls 15 feet, what velocity is gained at impact? Can this cause a concussion upon impact when striking a person in the face? Vertigo, nausea, headache….
Denise it dont take much to cause a concussion headache. But yes easly would cause a concussion. I being struck by a 57 lbs not 50lbs trunnion from 3 feet up to my face was a bad concussion i tried vomiting but ive never been the type to vomit lol. But i was lost in thought. So if i went out to get the mail i would take a turn to fix somethingand never make it to any of my tasks and then the headaches would make me almost cry and im 45 years young and i don’t cry ever. So later in the day after finding my self working at home on work leave my anger got very bad and this all went on for 1.5 weeks. But seriously i dont think it every goes away. Thank you foryour brilliant math skills and your time. Got dah love that math..
Denny
I’m trying to find out if 3-pound falls off a second-story building in Winds of 40 miles per hour how much will that 3-pound weigh when it hits an object.
I am disabled and am trying to design a complicated piece of furniture to accommodate my special needs , and I don’t know if what I want to do will work. It must withstand my 20 pound cat jumping down on it from a distance of about 3 feet. Am I right in thinking that the stopping distance would be difficult to establish, as a cat bends various joints as it lands, and cartilage and ligaments are in play also, to absorb some of the force of landing? After all, when he jumps on me, he isn’t landing with thousands of pounds of force, so even accounting for my flesh (if he jumps on my back, where my bones aren’t heavily padded), he is not landing with thousands of pounds of force. Also, when a cat falls from a height great enough to reach terminal velocity, which is high enough to give him time to get his landing gear and reflexes primed and ready to go, he can survive the fall. If he falls from a lesser height, he might not be hitting with as much force, but he will suffer more harm if he hasn’t gotten his landing gear and reflexes primed and ready to go. Obviously I would prefer that a cat, rather than a bowling ball, landed on me. I am guessing that since there is no way to know how to factor in the stopping distance of the cat, perhaps the thing to do would be to measure how many pounds of force he lands on a platform suspended from a luggage scale? They automatically record what the maximum weight they have weighed is. In that case, would the scale give me the final answer, or would I need to do some calculations after that?
@Neely Peterson
That’s a beautiful solution!
Unfortunately, you’re exactly right; to know the maximum force you’d need to know the impact time, so either way you have to fall back on experiment. If you’ve got a scale that tells you the maximum force, then you’re done. No extra math needed.
From behind me a 12 foot tall a-frame Werner ladder fall over sideways and the top of the ladder landed directly on top of my neck spine and shoulder how do I calculate the amount of force that my spine took? The ladder is rated at about 50lbs.
So out of morbid curiousity, how much force would a 30 lb sandbag have if it was dropped from a cargo plane at 5,000 feet?
I had spine fusion surgery almost a year ago, and my 40 pound dog jumped right on my back while I was doing yoga, she jumped from 1 ft and she weighs 40 pounds how much force did my spine take 😬 I weigh 110lbs
a bundle of copper 20 feet long wieghing 300 pounds containing 25 peices of 3/4″L x 20′ fell off my 24 foot flatbed work truck 4 feet to the ground while i was holding the other end 4 feet in not the very end the bundle was curled in my arms and i was looking to the left when i was jerked to the ground by ? amount of force i got neck shoulder and back injury landing on my butt any answer as to the amount of force jerked me down? injured in September of 2005.
So I dropped a piece of metal weighing 12.5 lbs that was 6in×3in from 5 ft in the air landing on the bone of my foot what is the impact force going to be I suck at math honestly please help cause I broke my foot and would like to know how much weight my foot took😬😲
I weigh 150 lbs. I fell 40 feet and hit the ground. I shattered my femur, both tibias and both fibulas. I broke four vertebrae and burst fractured another (my L5) I cracked 5 ribs and suffered numerous other injuries. What force did I hit the ground with? I’m not sure how to calculate.
I wonder if my foot is broken. 10 year old friend and I were using a 45 lb pry bar to squash the ground my foot got in the way and it hurt still swollen and bruised as of 9/23/2020
Someone dropped a 10-ft pvc pipe from approximately 6 feet straight onto my rt foot. The pipe doesn’t weigh a lot (approximately 5lbs) but has left me with nerve damage & not able to stand long without aggravating it. I am told I can’t be hurt bcs it’s not a heavy weight but with velocity would it be 5lbs x 6ft = 30 lb impact?
I’m trying to understand/explain “FPE”, an acronym used in ballistics to describe “Foot Pounds of Energy”.
For example, if there’s an airgun that fires
1. a 21.75 grain pellet (7000 grains = 1 lb)
2. at 400 FPS (feet per second)
It has an FPE of 7.73
One explanation I found was 1 FPE = the kinetic energy (force at impact) of 1 pound dropped 1 foot.
I also found that it was the force to move 1 lb (vertically?) 1 foot.
I’m guessing it’s the former, making a 7.73 FPE = to the impact of dropping 7.73 lbs 1 foot.
If you’d please explain, it would be much appreciated 🙂
Brent
After I had a stroke I fell two feet from my hospital bed directly onto the ball of my shoulder, my non working arm was trapped under me( I landed on about one Inchon my shoulder) (I’m about 200 lbs) I’m in severe pain the hospital only says nothing broken you had an X-ray “you must just be depressed”. My hand is in a claw that arm no longer works. How much pressure was exerted onto my shoulder where I landed during the fall thanks!
HI, I’d like to build a wood chopper with a 50lb axe head dropping from 12 feet. What would be the impact in pounds ? Thanks,denis
I used to be really into working out. Well, uñfortunately I used to just lift in shorts, no socks or shoes. Well, one day I picked up a 50lbs dumbbell and was working it up to my shoulders for shoulder presses behind my neck. Well, uñfortunately I got it about 3feet off the ground and it slipped out of my hands and landed on my barefoot. The pain was so bad, I began to feel like I might pass out while getting a ride to the hospital. My ride to the hospital said I began looking like super pale! How many pounds per square inch I suppose actually was dropped on my foot that led my big toe knuckle closer to my foot to crack?
I had a butcher block (size: 98” x 25” and weighing about 90lbs) leaning on a rail. While lifting a different butcher block over the rail, the one leaning feel and hit my right knee and headed down to smash my feet ( the left foot got the most damage). I stand about 5’7-8”. My question is approximately how much weight hit my knee and feet?
I was struck by a 53 lb solar panel. It dropped approximately 4ft on an angle of about 25-30 degrees to the right. How much force was I struck with if my hard hat had 1/4 inch padding? Math used to be easy, but now I have trouble calculating force. What weight measure do I use?