Warning, this topic is a bit gruesome, if that wasn’t apparent from the title.
I recently saw a trailer for Vertical Limit, in which, as in countless other action movies, a character falls some distance and then grabs on to something, arresting his fall.
How far can one fall and do this? Probably the hand grip would fail before the shoulder dislocates, so let’s separate it into two questions.
Take any year’s US Men’s Olympic Gymnastic team. Have them jump off a platform, under which, at increasing distances down is a horizontal bar, some modest distance (0.5 m) horizontaly from the top of the platform. Assume the bar is rigid, and 5cm in diamter (comfortable to grab). So they step off the platform, fall mostly straight down, reach out and grab the horizontal bar as they fall by and try to hang on. At what distance would 50% of them fail to hang on? (I’m guessing around 3m, after which they would be going 65 mph)
If somehow your hand would stick to the horizontal bar as you fell, what is the height that would dislocate 50% of the shoulders?
Getting more gruesome, is there a height at which the arm would…err… “fail catastrophically” i.e. rip out of shoulder or sever? Probably the place we would know this from is skydiving accidents, but I don’t see how one’s hand could get stuck on a cable. That is, the grip would fail before anything else.
More generally, is there a site to search for things like this in “The Medical Literature”?
The angle at which the arm is pulled (or pushed, in my case) makes a big difference. When doing the high jump in junior high, I came down (on a very soft surface) with my left arm underneath me, dislocating the shoulder. So in my case, it only required a height of 2 feet (from the top of my jump to the crash mat). While it probably takes more force to dislocate a shoulder by pulling the arm straight up, I’ve noticed that a lot of movie characters seem to have unrealistically sturdy joints.
Geoffrey Abbott’s Rack, Rope and Red Hot Pincers mentions a couple of interrogation methods that involve pulling or yanking arms out of their sockets (strappado and squassation, IIRC). I’ll check my copy when I get home from work to see if their are any useful details.
Also, once your shoulder has been dislocated, the damage done to the ligaments makes it much easier to dislocate your shoulder again, eventually resulting in folks who can pop their shoulders out at will (Mel Gibson’s character in Lethal Weapon, for example). After my first dislocation, the same arm came out seven more times that year until I finally had it surgically fixed. Since then, it’s never happened again.
Just wondering, but does muscle tone affect how easily one’s shoulder (or other joints) can be dislocated? I had zero upper body strength at the time.
a major factor envolved in the dislocation of the shoulder is the nature of the dislocation. The vast majorites are anterior dislocations (toward the front) also, how the shoulder was dislocated. A direct contact dislocation usually takes more force and does more damage. a dislocation that uses the arm as a lever takes much less force.
The amount of force needed to dislocate the shoulder is important in cases of abuse and would be well known in the orthopedics literature; I don’t know the numbers off the top of my head.
Essentially, the shoulder is a very shallow joint essentially held in place by external muscles. Trauma to the muscles, as mentioned, results in an anterior dislocation. POsterior dislocations are rare, but can be caused by epilepsy, electrocution and ECT.
Shoulder dislocations are quite painful but tend to happen quickly. Perhaps this would explain why the hand was still gripping.
Sorry, must dash, will be back with a more complete answer.
well it probably doesn’t take that much force, I dislocated my shoulder during a hook shot in basketball, I have a small benine(sp?) tumor on the ball part of the shoulder and it hit the socket and pop, it hurt like hell, it hasn’t happened since and I can’t do it at will which seems like it would be kinda cool
http://www.urbanlegends.com/death/falling_terminal_velocity.html Urbanlegends.com uses a semi-reliable source to give terminal velocity for a human body as being between 117-125mph in a random position at around STP.
About that 3m = 65mph thing. How’d you derive that exactly? I’ve jumped down from 3 meter heights into a roll before, but I can’t imagine it was 65mph…
My physics is very rusty, but I seem to calculate an object’s velocity after 3 meters as 17 mph?
Okay, assuming initial velocity and height are zero, you have an expression where distance = one half the velocity times time squared. (it works up to something, so pay attention)
So the time to fall one meter is the square root of twice the distance divided by the velocity, or about .5 seconds.
In that time, your velocity will reach 4.4 meters per second. Neat, huh? But get this, falling 3 meters takes about .8 seconds (both are rounded up).
In that time your velocity reaches 7.7 meters per second. Using my calculators nifty difty conversions…
Is 27.6 kilometers per hour or (if I understand my calculator) 40 feet per second…
Which works out to…
about 25 miles per hour (if there are indeed 5781 feet in a mile)
So, after falling three meters, if a drunk Surgo is infallible, you are travelling 25 mph.
Oh, and http://www.snopes.com deals with the superheated mug of water. They say that it could happen (it happened to my brother, though he wasn’t blinded), so if you’re worried, put in a spoon.
This isn’t a pad, I’m drunk, so let me be, I’m trying to be helpful.