Michael Schumacher in critical condition

[Matthew Best]

My current point of view is that the neurosurgeons and trauma teams at the hospital in Grenoble - which is the regional go-to hospital for serious alpine accidents - might well have plenty of experience correlating speed at impact with extent of brain trauma and damage caused to helmets

What exactly have they said about it?

 

[LondonJohn]

Like I said, Fritz Wunderlich tripped and fell on a stone staircase. Stuff happens.

Rolfe.

Very true. I might trip on the pavement on my way to buy a pint of milk tomorrow, catch the edge of the kerb with my head, and suffer a fatal head injury there and then.

But in life (whether "normal" day-to-day activities or recreational activities), there is always a balance of risk versus utility. Every activity has SOME level of risk, but in most cases the risk levels are so relatively low that the utility gained by carrying out that activity more than offsets any risk. For example, it's such a low possibility that I will be seriously injured or killed (by any factor) from the action of going out to buy milk tomorrow that this super-low risk is obviously far outweighed by the benefit I will gain from obtaining the milk.

And the same is true - except more markedly - in recreational activities. Especially more "extreme" sports. Everyone who skis (and who stops to measure the risk) is implicitly accepting the significant risk of orthopaedic injury, but offsetting that risk against the enjoyment, excitement and physical exertion to be gained from skiing. That's the implicit bargain that skiers strike with themselves.

I ski and scuba dive. Both activities can be fatal (particularly scuba), and both carry significant risks of serious injury. But I make the implicit assessment that my enjoyment of these activities is "worth" the risk, and I do all that I can to mitigate the risk by following protocols and skiing/diving within my capabilities.

And what I'm arguing with specific regard to Schumacher's accident is that he apparently made a conscious decision to ski in a high-risk manner. There are clear possible "benefits" from engaging in this sort of skiing as opposed to sedate on-piste skiing: the adrenaline rush, the feelings of taking on a challenge, the testing of oneself physically and mentally. But as a quid pro quo, there are also clearly higher risks. I argue that Schumacher implicitly weighted up the "costs" and "benefits" of skiing in this manner, and obviously decided that the additional risk was more than offset by the "benefits" to him. That's fine. That was his choice. I am not criticising him for making that choice. But it's utterly undeniable that by making that choice, Schumacher exposed himself to otherwise-avoidable additional risk of serious injury or death.

 

[angrysoba]

I think you are the one failing to following the line of thought. The claim was that he was going very fast for a "recreational" skier. My point was that he was an "expert" skier so it wasn't particularly fast at all.

The part you highlighted was "recreational skiiing", not a "recreational skiier", so you have moved the slalom gates.

 

[LondonJohn]

What exactly have they said about it?

Well there appears to be a leak to the media from "sources close to the investigation" that the indicated speed was something between 60km/h and 100km/h, which correlates to between 37mph and 62mph:

http://www.thetimes.co.uk/tto/news/world/europe/article3961630.ece

I've also seen reports that state that the speed is likely to have been close to the upper limit given in this range.

I would think that these numbers are arrived at by a combination of liaison with the medical teams (who, as I said, will have extensive experience matching extent of injuries to impact speeds), police crash specialists, and maybe also insurance specialists. I would imagine that it's often very important for insurers to have educated knowledge about speeds of impact in skiing accidents, since it may have a material effect upon liability (which is exactly why there's just a possibility that Schumacher's manager might have a vested interest in promoting a "lower speed of crash" (= "not reckless") story).

 

[LondonJohn]

ETA: Note that even the low point in this range - 37mph - is still very fast to be travelling through a pretty dense boulder field.

 

[Orphia Nay]

Bearing in mind that he "hit a rock and was catapulted into the air then hit a rock with his head", the speed at which he fell onto the second rock is not necessarily the speed at which he was skiing.

 

[angrysoba]

Bearing in mind that he "hit a rock and was catapulted into the air then hit a rock with his head", the speed at which he fell onto the second rock is not necessarily the speed at which he was skiing.

I'm not an expert at this but I would have thought his skiing speed would have been faster than the speed at which he hit the rock from being in the air, unless he plummeted off a very high cliff, because I don't think skiers pick up speed in mid-air.

 

[LondonJohn]

Bearing in mind that he "hit a rock and was catapulted into the air then hit a rock with his head", the speed at which he fell onto the second rock is not necessarily the speed at which he was skiing.

Well, strictly speaking this is true. But conservation of momentum and conservation of energy both suggest that it's likely that there was a close correlation between skiing speed at impact and speed of impact on the second rock.

Bear in mind that the only thing that could have caused increased momentum or increased kinetic energy between the initial rock-hit and the point of hitting the second rock with the head is acceleration due to gravity. And the only additional momentum or KE gained due to gravity would only be due to the difference in height between the point at which he was "catapulted" and that point at which he hit the rock (since even if he was catapulted high into the air, this height would all be resultant from the momentum and KE of Schumacher at the point of initial impact).

So in practice the velocity at which Schumacher was travelling at the moment when his head hit the rock is probably very closely related to his speed over the ground at the point of initial impact. In fact, the head impact speed in such a scenario is likely to be slightly slower than the ground speed at initial impact, since an amount of momentum and KE would have been dissipated in the initial impact.

(Of course this assumes that the head did not "snap" in a whiplash manner at the point of head impact, which would obviously affect the velocity of head impact since the head would be moving at a different speed to the rest of the body, but I think it's unlikely that this would have been a significant factor)

 

[LondonJohn]

I'm not an expert at this but I would have thought his skiing speed would have been faster than the speed at which he hit the rock from being in the air, unless he plummeted off a very high cliff, because I don't think skiers pick up speed in mid-air.

You beat me to it! However (as I pointed out above), it is possible that the additional drop in height between initial point of impact and point of head impact may have resulted in a slight increase in speed.

 

[Cool Hand Luke]

I'm not an expert at this but I would have thought his skiing speed would have been faster than the speed at which he hit the rock from being in the air, unless he plummeted off a very high cliff, because I don't think skiers pick up speed in mid-air.

Well, strictly speaking this is true. But conservation of momentum and conservation of energy both suggest that it's likely that there was a close correlation between skiing speed at impact and speed of impact on the second rock.

You beat me to it! However (as I pointed out above), it is possible that the additional drop in height between initial point of impact and point of head impact may have resulted in a slight increase in speed.

.
Nope, nope,nope, nope, nope. You're all neglecting one important aspect (although LondonJohn did hint at it before partially dismissing it).

When a skier falls they tumble. That tumbling action - or "whiplash" as LondonJohn referred to it - can actually greatly increase the impact velocity of various body parts when they finally meet an immovable object.

If Schumi was tumbling head-over-feet then the impact velocity of his head on the rock was his raw forward velocity upon striking the first rock + velocity gained through gravity (minor) + angular velocity resulting from the tumble. Depending on how the fall occurs the angular velocity can actually add substantially to the velocity of the impact. In some cases it can account for the majority of the impact velocity.

And no, this doesn't violate conservation of momentum. Part of the force that went into the first collision is responsible for starting the tumble. It takes very little force to rotate a body as opposed to lifting it or changing it's speed or direction. Think of how easy an ice skater is able to convert a small amount of speed and some muscle into a tremendously rapid spin. You can generate huge angular velocities in objects with relatively little force.

So in the end the speed he was going when he fell has more to do with why he fell than the nature of his injuries. You can crack open yur noggin' just as nicely on a green circle trail as you can on a double black diamond. You can be going downhill at 10kph and take a spill that results in a 50kph impact. It all depends on how you fall.

Cheers,
Luke.

 

[qayak]

.
Nope, nope,nope, nope, nope. You're all neglecting one important aspect (although LondonJohn did hint at it before partially dismissing it).

When a skier falls they tumble. That tumbling action - or "whiplash" as LondonJohn referred to it - can actually greatly increase the impact velocity of various body parts when they finally meet an immovable object.

If Schumi was tumbling head-over-feet then the impact velocity of his head on the rock was his raw forward velocity upon striking the first rock + velocity gained through gravity (minor) + angular velocity resulting from the tumble. Depending on how the fall occurs the angular velocity can actually add substantially to the velocity of the impact. In some cases it can account for the majority of the impact velocity.

And no, this doesn't violate conservation of momentum. Part of the force that went into the first collision is responsible for starting the tumble. It takes very little force to rotate a body as opposed to lifting it or changing it's speed or direction. Think of how easy an ice skater is able to convert a small amount of speed and some muscle into a tremendously rapid spin. You can generate huge angular velocities in objects with relatively little force.

So in the end the speed he was going when he fell has more to do with why he fell than the nature of his injuries. You can crack open yur noggin' just as nicely on a green circle trail as you can on a double black diamond. You can be going downhill at 10kph and take a spill that results in a 50kph impact. It all depends on how you fall.

Cheers,
Luke.

Pretty much what I was thinking. People often forget that velocity is a vector with both a magnitude and a direction. Acceleration doesn't only happen when there is a change in speed, it also happens when there is a change in direction.

ETA: Also, a falling body can fall faster than gravity allows under circumstances found in falls. The centre of gravity falls towards the earth due to gravity which puts a lot of extra force on the top part of the body, ie.- the head causing it to strike with more speed and thus more force. This is the reason smoke stacks break in half when they are demolished.

 

[cullennz]

Putting aside the how fast convo' I hope he doesn't suffer too much paralysis or aphasia (sp?) or both.

From experience with someone close to me it is not nice.

 

[Orphia Nay]

Richard Hammond talks about Michael Schumacher's accident and possible recovery:

http://www.mirror.co.uk/sport/formula-1/richard-hammond-michael-schumachers-accident-2974233

 

[qayak]

Here is an example of the forces involved in this type of fall. This is a video from the 1980s of Canadian Todd Brooker taking a spill at Kitzbuhel, Austria during a World Cup downhill event.

WARNING: This maybe traumatic to some people. Just remember he lived with few if any lasting issues. As he puts it, "Everyone remembers that fall except me!"

 

[Cool Hand Luke]

Here is an example of the forces involved in this type of fall.

.
And that, my friends, is why Luke does not ski.

 

[LondonJohn]

.
Nope, nope,nope, nope, nope. You're all neglecting one important aspect (although LondonJohn did hint at it before partially dismissing it).

When a skier falls they tumble. That tumbling action - or "whiplash" as LondonJohn referred to it - can actually greatly increase the impact velocity of various body parts when they finally meet an immovable object.

If Schumi was tumbling head-over-feet then the impact velocity of his head on the rock was his raw forward velocity upon striking the first rock + velocity gained through gravity (minor) + angular velocity resulting from the tumble. Depending on how the fall occurs the angular velocity can actually add substantially to the velocity of the impact. In some cases it can account for the majority of the impact velocity.

And no, this doesn't violate conservation of momentum. Part of the force that went into the first collision is responsible for starting the tumble. It takes very little force to rotate a body as opposed to lifting it or changing it's speed or direction. Think of how easy an ice skater is able to convert a small amount of speed and some muscle into a tremendously rapid spin. You can generate huge angular velocities in objects with relatively little force.

So in the end the speed he was going when he fell has more to do with why he fell than the nature of his injuries. You can crack open yur noggin' just as nicely on a green circle trail as you can on a double black diamond. You can be going downhill at 10kph and take a spill that results in a 50kph impact. It all depends on how you fall.

Cheers,
Luke.

Nope, nope, nope etc......

Without wishing to labour the point, the tumbling that occurs in a skiing accident is almost always as a result of the friction of contact with the slope, and occurs when the skier is in frequent repeated contact with the slope. Furthermore, if a skier is travelling at moderate or low speed, there's minimal tumbling, if any.

I am assuming from your posts that you have never skied. But anyone who has skied - and has therefore fallen over many times - is well aware of the mechanics of falling. For example, I have never once tumbled after hitting an ice patch or losing control: the most I've done is rolled a couple of times. I'm a moderate-skill skier, and mostly ski on blue or red runs, probably reaching speeds of up to 20-25mph maximum. I guarantee that to get "catapulted" or to tumble end over end, one needs to be skiing at a significantly higher speed than that.

In addition.in Schumacher's case, the reports suggest that he hit a rock, "catapulted" into the air, then hit his head on a second rock. If this is accurate, then the head injury likely arose prior to any potential tumbling that may subsequently have taken place.

What's more, if Schumacher had hit the initial rock with enough force to send him catapulting end-over-end into the air, then by definition he would have to have been travelling at very significant speed in any case. Much more likely though (and as seems to be suggested by the eyewitness statements), Schumacher hit the rock and left the ground without somersaulting, before hitting another rock further down the slope.

In fact, either way one looks at it, all the evidence suggests significant speed. If Schumacher did indeed get ejected upwards in this "catapult" motion, then this in itself is strongly suggestive of a fast downhill speed prior to the initial impact. It takes a lot of forward momentum to cause an skier to leave the ground for a significant distance in such circumstances; a skier travelling at moderate to slow speed (i.e. less than 15mph) would almost certainly simply crash straight to the ground after such an impact.

I saw Schumacher's manager again making very insistent statements that he was only travelling at low speed at the time of the accident. I repeat the possibility of an ulterior motive (but that's not to say that there IS an ulterior motive).

Simply put, a skier travelling at low speed is highly unlikely to sustain an impact sufficient to cause the cracking of a properly-constructed skiing helmet, no matter what tumbling or somersaulting takes place (and remembering that such tumbling/somersaulting is minor for low-speed accidents)

 

[LondonJohn]

Here is an example of the forces involved in this type of fall. This is a video from the 1980s of Canadian Todd Brooker taking a spill at Kitzbuhel, Austria during a World Cup downhill event.

WARNING: This maybe traumatic to some people. Just remember he lived with few if any lasting issues. As he puts it, "Everyone remembers that fall except me!"

When you say "this type of fall" you're aware (I assume) that the skier in this video was probably travelling at 60-70mph at the moment of lost control, on racing skis.

A skier crashing or falling at 15-20mph (or even lower, as Schumacher's manager seems to be claiming) behaves in nothing remotely approaching this manner.

 

[LondonJohn]

Pretty much what I was thinking. People often forget that velocity is a vector with both a magnitude and a direction. Acceleration doesn't only happen when there is a change in speed, it also happens when there is a change in direction.

Very true. But not really applicable to our situation. And any and all acceleration in any given direction HAS to be as the result of an applied force (F=ma, or a=F/m). The only external force acting on Schumacher post-impact was gravity, acting in a purely vertically-downward direction.

ETA: Also, a falling body can fall faster than gravity allows under circumstances found in falls. The centre of gravity falls towards the earth due to gravity which puts a lot of extra force on the top part of the body, ie.- the head causing it to strike with more speed and thus more force. This is the reason smoke stacks break in half when they are demolished.

Unfortunately, this is nonsensical from a scientific point of view. A body cannot accelerate downwards faster than g (acceleration due to gravity) without some other external force being applied with a vector component in the same downward direction.

It IS correct, however, to say that issues such as angular momentum (e.g. tumbling) or elasticity effects may cause certain parts of a body falling under gravity to travel temporarily at a higher speed than that of the centre of gravity (which will always travel at the velocity obeying v=u+at). But these are temporary and self-cancelling effects: if one were, for example, to map the velocity of the head of a person tumbling downwards, the times when the head was travelling faster than the centre of gravity would be exactly cancelled out by the times when the head was travelling slower than the centre of gravity (the feet would be travelling faster at this point).

As an aside, the reason why smoke stacks break in half when demolished is because the load is never exactly equally spread around the entire circumference of the stack (owing to slight leans and slight differences in the strength of construction, and a slightly unsymmetrical detonation charge). once the vertical load "finds" a weak spot, the additional load will cause this spot to fail first, and thus cause the stack to fracture at that point (this is a very simplified explanation). If a stack were of perfect construction and perfectly vertical, and exactly equal detonation charge were placed all around the base circumference, then the stack would always collapse exactly vertically.

 

[bruto]

I don't know that much about ski helmets, but thinking about them in comparison to bicycle helmets, I would point out that although a helmet can prevent all sorts of damage, contact with a rock cancels most bets. I've seen a bike helmet broken by a rock at not much more than walking speeds. If you hit one rock at the right point, the helmet breaks and you walk home. If you tumble and hit two rocks a significant part of the helmet's useful life has already been spent. I doubt you can meaningfully compare this accident to one that occurs at any speed on a rock free slope.

 

[Jim_MDP]

I don't know that much about ski helmets, but thinking about them in comparison to bicycle helmets, I would point out that although a helmet can prevent all sorts of damage, contact with a rock cancels most bets. I've seen a bike helmet broken by a rock at not much more than walking speeds. If you hit one rock at the right point, the helmet breaks and you walk home. If you tumble and hit two rocks a significant part of the helmet's useful life has already been spent. I doubt you can meaningfully compare this accident to one that occurs at any speed on a rock free slope.

Not sure, but I think the lids used on slopes are closer to motorcycle helmets than bicycle types. It's been ~12 years since I had to quit and they were only just starting to be seen outside of the little terroristic ankle-biters. Damn helmets made them feel invincible and they skied like it.