Carnac, your analysis ignores the vehicles suspension. Wouldn’t that also come into play?
First off 4000 lbs would be a damn small SUV. 6000 would be closer to the mark. Some (Hummer) are closer to 8,000.
I agree, having a car roll over your foot would be a bad thing.
First of all, the OP should read “Would it hurt to have my foot run over?” The car ran over your foot. Your foot was run over. I ran over your cat. My dog was run over last year.
Anyway, my mother ran over the back of my foot after dropping me at school once. The tyre kind of climbed over and up the back of my heel. That hurt a lot, but no damage really; just a bit of hopping around and swearing, then I continued with my day.
I would agree that a large truck would probably be less of a problem - due to the reasons above, and the fact that the tyres are so wide that even if they ran over your foot there would still be a large proportion of the tyre in contact with the road beyond your toes.
carnac’scalculations aside, I had my foot run over by by a midsized sedan full of crap (people moving) and a few toes were a little sore, but not even really all that bruised. Scuffed my shoe something wicked, though.
Variables are everywhere, tire strength, vehicle weight and distribution, speed, foot angle, ground condition, shoes, etc. My guess is that the damage to DougC’s cop and FlippyFly’s Wrangler experiences were because the body was moving and the foot was not (since there was a car on it) which tends to lengthen things that shouldn’t lengthen.
I think that the key difference with my experience was that the foot was on the side, not in a normal standing position. Once again, the toes were in a verticle column.
The OP said “any car.” I used the SUV example to illustrate a point and chose a smaller SUV (my Honda Pilot at 4400 lbs) to be conservative. Yes, a “deathstar SUV” certainly weighs more, but also has somewhat larger tires. Bottomline: ouch!
If by “large truck” you are including an 18-wheel “tractor trailer” filled with cargo, then we’re looking at 80,000 lbs (40 tons) of nearly dead weight, or 4,400 lbs per tire, if evenly distributed. Better eat your spinach, Popeye.
Whatever harm right tire #1 causes will pale next to what happens when right tire #5 finally transitions from flesh to asphalt. Distribute 22,000 lbs. any way you wish, the final result is apt to go squish, squish, squish.
P.S. A U.S.-made M1A2 battle tank weighs more than 65 tons and rolls on rather unforgiving steel treads. :rolleyes:
My first job when I turned 16 was working as a service station attendant. We were required to wear steel-toed safety shoes in case customers drove over our feet.
Part of the initiation of new guys involved sending them accross the street to the Canadian Tire store to buy a skyhook for the mechanics, and a “safety confidence demonstration” which involved driving over your new safety shoe, foot still inside, with the tow-truck. Of course they then parked the tow truck on your foot and left you stranded for a while. Did I mention they would do this just before the canteen truck rolled in with dinner… It was hillarious…for everybody else…
I assume that “bad things” had happened before of the squashed feet sort. This company never had a safety rule that wasn’t written in the blood of some previous accident.
Re Carnac’s calculations, in my driver’s ed course, they told us the contac patch was about 3 inches long on most cars, which, when multiplied by the width of the tire, adds up to a lot less area, thus showing Carnac’s assumptions to be conservative, and the pressure to be even higher. In my mind, the major factor is the hardness of the underlying surface. In a softer surface, like gravel, the tire will sink, increasing the contact area until the pressure is low enough to be borne by the surface material, at which point the wheel stops sinking. Conversely, it the surface is hard, the contact patch is smaller.
Consider trains., The reason trains are so efficient is that they ride on hard steel wheels on hard steel rails. The contact area for a train wheel is tiny, and there is little deformation of the wheel as it turns. This is what makes the rolling resistance of a train so low, and allows a couple of locomotives to pull so much weight. But this is also what makes the pressure under a train wheel so high that it acts as a blunt scissor…
I’m not saying it’s a good idea to put yourself underneath a tank. [KIDS: DON"T TRY THIS AT HOME!]
But it’s not completely insurvivable.
To quote http://www.answers.com/topic/caterpillar-track-1
For comparison, when I step on your foot, it’s 180 pounds over, say a generous 3 inches by 3.3 inches, or 18 psi. (that’s static, of course. If I go up for a rebound and land on your foot, the pressure is much higher).
I admit that any nasty hard and sharp metal pieces on a tank tread could be unpleasant, but the general point is that the whole system is designed for low ground pressures.
When I was 10, my Little League coach accidentally backed over the front of my foot with his late-60s Chevy Nova. The foot was laid flat, and the tire only covered about 3-4 inches. It hurt a lot, but there was no damage. It was on a gravel parking lot.
He would have been completely justified in bawling me out for not paying attention, but was very concerned and sympathatic, telling us that he had recently suffered a similar fate, with a much bigger car (a Riviera :eek: ).
[quote]
…The key figure isn’t the weight of the vehicle, it’s the pressure-- roughly, the weight of the vehicle divided by the area of all of the tires… [.quote]
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- This is true–but another thing to consider about that “pressure” is that typical car/light truck tires are inflated to about 30-35 PSI, where large truck tires are often inflated to 80 PSI or more. Some truck tires are inflated to 120 PSI.
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- Also I am remembering a loaded cement truck to weigh about 60,000 lbs. As they have ten tires, that’s (average) 6000 lbs per tire, quite a bit more than the 1500 lbs per tire of a “big” 6000-lb SUV…
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This may be going against the tide of the thread but…
My niece had her foot run over be a FEDEX or UPS truck when she was about 10. I’m not sure if it rolled over or stayed on a while, but in any event there was much damage. There was significant swelling, to the point that the doctors at the hospital had to make many incisions in the flesh of her foot to release swelling pressure - something about otherwise the blood circulation would be cut off and the foot would necrify. She was in the hostpital for several days, then a period of months of recovery. One of the big concerns was if there would be damage to something called the ‘growth plate’ inhibiting further development.
That was several years ago and she seems to have turned out OK, thank goodness. But I am surprised there are so many reports here of little or no damage.
Wouldn’t the key thing here be whether the wheel or tread has to lift off the ground in order to get over your foot ? This would dramatically in increase the force pressing down on your foot. If the tyre was at a low pressure or was just moving over your toes it would not have to lift up and you would be ok If it ran over the arch of your foot however, you would suddenly be supporting 1/4 the weight of the car.
A tank rolling over you it would have to lift up to get over you, removing much of the track from contact from the floor, this would likely result in you getting squished.
I’m not an engineer however so I’m probably adding to the afformentioned bullshit quotient, but the above makes sense to me.
If a horse qualifies as a vehicle, then I have had my foot run over. When I was about 16, my foot was stepped on by a very big horse. It hurt like hell for a day or two, but no damage was done and I still feel fine. That was 60 years ago. :rolleyes: