Calculating Impact Force: Travis Struck by Object at Work

[tarful]

A few months ago I was at work in the oilfield. I was struck by some tongs along the right side of my face.

To simplify everything:

I was moving toward the tongs at 3mph. I am 6'1" and was struck by an object 3" thick around 5'6" off the ground. (my cheek) The tongs were moving around 70 mph and weigh in around 750 lbs. Let's assume they were right angles , no movement on my part (whiplash, absorbsion by neck movement).. just a simple answer of how hard I was hit in psi or impact force or whatever can be derived from the information I have stated.

Thanks in advance

Travis

 

[berkeman]

It's a trick question. If you were hit in the head by 750 pound tongs moving at 73mph, you could not post this question.

 

[tarful]

I posted a pic of me in the hospital. Lower jaw, upper jaw, orbital socket, nose and pallet were broken in at least one spot. Ending result is 7 plates and 53 screws.

So, someone can live through it. I just wanted to know what the worst impact could have been.

 

[berkeman]

Yikes, I didn't even notice the pic attachment. I'm glad you're alive, tarful. Best wishes for your recovery.

 

[Danger]

Glad you survived, Tarful. I have to agree with Berkeman, though; it must have been a glancing impact, which would make it very difficult to determine how much force was actually applied to you. If it came straight at you, you shouldn't be here. Think of comparing it to someone dropping a bowling ball on your head from a second-floor window... the tongs would have had more energy than that by a long way.
I hope it's not too long before you can enjoy a steak again.

 

[tarful]

Been eating steaks for a long time. Well, about 6 weeks anyway. The injury happened June 9 2006 at 7:12 pm .. lol i don't think i'll forget that date.

So, what formula can I punch into find out what force those tongs had when they were moving. I just want to see the potential of those tongs. Alot of people have asked me how much force the tongs produce when they snap like that. I just wanted to see if I could give them an answer.

Thanks for all the kind words.

 

[berkeman]

So, what formula can I punch into find out what force those tongs had when they were moving. I just want to see the potential of those tongs. Alot of people have asked me how much force the tongs produce when they snap like that. I just wanted to see if I could give them an answer.

Force is the the acceleration of an object multiplied by the mass of the object, or as we usually write it, F=ma.

Here is a wikipedia article to give you more information:

http://en.wikipedia.org/wiki/Force

 

[Danger]

I just want to see the potential of those tongs.

Now that Berkeman has shown you where the formulae are, we'll let you work it out for yourself. Leave it suffice to be said that I don't think many cars would have survived an encounter such as yours.

 

[russ_watters]

These guys are right - I don't think anything you can caluclate here would be at all useful. The kinetic energy of this object at 73 mph is equal to if it had been dropped onto your face from about 180 feet. That's a full dumpster dropped on you from ten stories.

Suffice to say, when it hit you, it simply knocked your face out of its way.

 

[Bystander]

Figure 2-3" of crushing and distortion of facial bones and tissues, and you're looking at 2-3 milliseconds contact time (you didn't slow the tongs down enough to matter too much in the calculation). 2-3 milliseconds to get you to 100 fps? A "square" hit gets you to the 1000 g neighborhood. 200 g is fatal (basal skull fracture) for race drivers w'out exotic head restraints built into helmets. Crush your head flat in 5-6 ms, and you're down to 400-500 g. Add a couple inches (and ms) for mashing your hard hat --- or did this give you an "uppercut?" You are one lucky roughneck.

 

[russ_watters]

Yeah, I was thinking about that on my ride home - the kinetic energy of the tongs don't matter because that energy isn't transferred to your face. All you have is the energy of your head being accelerated to 73mph.

Your face acts like a "crumple zone" in a car here - the crumpling adds distance and therefore time to decrease the acceleration/ acceleration force.

 

[tarful]

I'm back

"Your face acts like a "crumple zone" in a car here - the crumpling adds distance and therefore time to decrease the acceleration/ acceleration force."

That is what the doctors told me. I have been away for a while, work has been busy. I agree with your statements about my head being in the way of the tongs didnt really matter.

I finally got a copy of some xrays on cd, I'll show you the end result. It might take me a few minutes to convert to something I can post here.

 

[tarful]

See if this works

http://photos.yahoo.com/tarful

Count the screws!

 

[Danger]

They're going to love you at airports.
Bloody hell! I haven't had that many screws since I got married. I guess future MRI's are out of the question.
By the bye, I believe that those are clamps, not scissors.

 

[tarful]

renamed properly thanks

plates and screws are titanium.. so no worries at the airport