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OT but interesting is the information reported during the recent F1 race at Spa. A F1 car can brake from 190mph to 50mph in less than 2 seconds! Can you imagine what this feels like to the driver?


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Malcolm W.
The views expressed in this post are personal opinions and do not represent the views of Safespeed.

Martin Brundle explained it with great lucidity once, in that you brake with such a force that any tears in your eye fall out of it horizontally and splashes onto your visor right in your line of sight.

Muddy hell - that is over 3Gee!!

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

If you stop much faster you can get up into the hundreds of g's:

http://www.youtube.com/watch?v=aVpux5JxqEk

So you agree it's not speed that kills but the sudden deceleration, or acceleration if you are hit.

We got there eventually…

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The views expressed in this post are personal opinions and do not necessarily represent the views of Safe Speed.
You will be branded a threat to society by going over a speed limit where it is safe to do so, and suffer the consequences of your actions in a way criminals do not, more so than someone who is a real threat to our society.

No absolutely not.

John P Stapp spent years convincing people who thought there was no point in putting safety systems in cars to do so; the reasoning was that the deceleration would kill you anyway so why bother. He proved this was not the case.

IIRC he was tasked to find out why so many pilots died young and actually found they weren't dying in plane crashes but driving to the airfield in their cars.



http://en.wikipedia.org/wiki/John_Stapp ... celeration

Speed on its own cannot kill (people have travelled in excess of 100mph, even a few at supersonic speeds – they lived).
You say deceleration (rate of change of speed) cannot kill.
So what does?


He has not disproved there is an upper limit that one could withstand. It seems that sudden deceleration (beyond a certain level) can kill - which is obvious really!

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Views expressed are personal opinions and are not necessarily shared by the Safe Speed campaign

Ignoring crush and penetration injuries it is the differential acceleration that gets you. After all if every molecule of your body accelerated at the same rate you would not even notice. What kills you is the forces between various parts of your anatomy due due to their relative acceleration rates.

Everything is relative

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Driving fast is for a particular time and place, I can do it I just only do it occasionally because I am a gentleman.
- James May

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Views expressed are personal opinions and are not necessarily shared by the Safe Speed campaign

But all those safety systems are ways of reducing the deceleration of the body in the car. Seat belts and airbags stop you going forward and suffering immense deceleration as you hit the windscreen.

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

Trauma caused by pressure of one object on another as I understand it.

So stop me dead in space by grabbing me from behind and I'm probably going to be ok (saved for maybe some damage caused by my organs banging together) but stop me dead by putting up a big wall and I'm going to be quite a mess.

No, seat belts stop you smashing against stuff in the vehicle (or outside it if you manage to be ejected).

Again it's not the deceleration that gets you, it's smashing against other stuff, a well tightened restraint harness stops this happening, case in point F1 drivers that have crashed and been subjected to 200G+ with little or no problems.

"Smashing against other stuff" is deceleration. Your body reduces its speed from something to nothing in a very short time. Delta speed over time is acceleration; thus the shorter the time the greater the acceleration

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

So what is it when you slow down and don't smash into stuff?

I can put myself in a full contact harness and send myself along a rocket sled and have that brake and not actually smash into stuff and then walk away.

A racing driver is not saved by the seat belts, but rather by the combination of belts and shock-absorption provided by the progressive collapse of the vehicle, that reduces the Deceleration to a survivable level.

A graph[ical display] is worth a thousand words:

http://www.skytran.net/04Technical/pod08.htm

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The world runs on oil, period. No other substance can compete when it comes to energy density, flexibility, ease of handling, ease of transportation. If oil didn’t exist we would have to invent it.”

56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing

This is going to read as insulting, however it is more of an apology.

Some time ago I made a comparison of weepej's thoughts about motorists to racism. This I can now see was unfair.

Reading the last few posts makes it clear that at least some of his ideas come from an ignorance of basic physics. This is not unusual, most people are in the same boat as much of it is counter-intuitive.

E.g. articulated lorries jackknife when the rear wheels lock.

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Driving fast is for a particular time and place, I can do it I just only do it occasionally because I am a gentleman.
- James May

Most scientists exhibit an ignorance of physics. And of laws of same. They're called, collectively, climatologists!

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The world runs on oil, period. No other substance can compete when it comes to energy density, flexibility, ease of handling, ease of transportation. If oil didn’t exist we would have to invent it.”

56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing

Hmmm.

So take an apple. I'm going to put it in a harness, tie a rope to the harness, project it forward and when the rope runs out of slack the the apple is going to be subjected to a 200g stop, i.e. it's already in contact with what decelerates it.

Now throw the apple at a barrier where it's subject to a 200g stop.

What would be the result in both situations? Genuine question.

I think we need to be a bit careful with things like that Youtube video clip. I very much doubt that the DRIVER saw a 200+G deceleration, (or anything like it) but I can believe that the bit of car to which the accelerometer was attached, might have done! In crash test work, it's not sufficient to specify an acceleration, you also need to specify a time. If I flick your ear lobe, I can probably give it a very large acceleration, but it's unlikely to kill you. If I tap the steel bonnet of a car gently with a tack hammer, I'll probably (locally) give the bit immediately under the hammer head a massive acceleration - several hundred G, but not do the car, as a whole, any real damage. A steel-tyred cart pulled by a horse over a cobbled street is likely to feed enormous accelerations up into its wheels, but the durations are so short that the energy put into the wheel isn't that great. up until they introduced the new "Hybrid II" crash test dummies and more complex ways of working out injury levels, they used to work on about 80G as a maximum surviveable head deceleration - and I think they allowed "spikes" uf up to 3 milliseconds duration as high as 120G. The big internal organs can't take anything like that though. I think a lot depends on the physiology of the person. Clearly, a fat git such as myself, with poor muscle tone wouldn't be able to withstand anything like the sort of deceleration of a sportsman. Obviously, the filtering of the raw data from the accelerometer is critical. You can see horrendous accelerations in the raw data but they're usually "noise" caused by "ringing" of the structure to which the accelerometer is attached.

Much the same - assuming the same area of apple was in contact with the rope and the barrier - apple sauce!