subaqua
What’s the point
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when did helmets stop G force ? they stop a very very very small impact force only.
Knocked off my bike in a cycle lane
- Thread starter annirak
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when did helmets stop G force ? they stop a very very very small impact force only.
They reduce the impact speed which in turn reduces G.
a compression or deflection of 5mm can reduce the G by 50% #(from memory)
I did all this in another discussion on how fast will I be travelling if i jumped off my bike (anyone who was on it may remember Imade a spectacular cock up at the end of that one )
So in order for a helmet to break, it must deform, that act of deforming is the same as the foam compressing - that absorbtion of the kentic energy of the missile (the head) will reduce the G the brain is subject to.
Brains start taking damage at 10g
a compression or deflection of 5mm can reduce the G by 50% #(from memory)
I did all this in another discussion on how fast will I be travelling if i jumped off my bike (anyone who was on it may remember Imade a spectacular cock up at the end of that one )
So in order for a helmet to break, it must deform, that act of deforming is the same as the foam compressing - that absorbtion of the kentic energy of the missile (the head) will reduce the G the brain is subject to.
Brains start taking damage at 10g
classic33
Leg End Member
@Licramite
If the brain only starts taking damage at forces of 10g, what speed would the head need to be travelling in a "log fall"?
That is a straight back, with impact on a solid surface.
If the brain only starts taking damage at forces of 10g, what speed would the head need to be travelling in a "log fall"?
That is a straight back, with impact on a solid surface.
I find if you don't know what you're talking about, it's best to remain silent on a topic.
Quick check on fall G calculator
2m drop - 2cm stopping distance = 100g
if anyboby fancies checking what the equivalent weight of your head is under 100g look it up on the inde car racing site. - its a bit scary.
Brain damage starts with bruising, at 10g it starts to bruise
we have all had minor brain damage in our lives
just for fun check out what the g is with 0 stopping distance
anything over 200g is not recommended.
don't blame me - blame google
winjim
Smash the cistern
It's probably alright then.
OK, I'll take the claims you made in the previous post one by one.
Incorrect. They might, they might not. It depends on the situation, the direction of impact, and a host of other variables.
Incorrect. Again, entirely dependent on many many variables.
Incorrect. Polystyrene can break immediately, with no compression, depending on the amount of energy and the direction of stress. Example: get a packing piece from a TV box or something. You can snap it in your hands like a piece of spaghetti without it compressing at all.
Incorrect. It might. It might not. It might increase the g-force on the brain, if it snags and causes additional rotation.
Incorrect. Some damage has been observed in cases as low as 10g; others have shown no damage in over 50g.
So as I said above: if you do not know what you are talking about, you should remain silent on it.
lets answer in order
1) so they might - so you cannot say if I'm correct or not.
2)again - many factors doesn't rule it out - it can still happen.
3)your saying polsyrene breaks with NO Force being applied? - whats just breaks, I think force has to be applied or your physical world is different to mine.
4- so it might - so theres a possibility it does.
5-the brain starts taking damage at about 10g, - this is the start point, you may not even know it, it may not have any symptons - if someone is showing signs it means they have taken way more than 10g of damage.
6g is enough to stop blood getting to the brain - and what happens if starve an organ of blood - it doesn,t improve thats a fact.
classic33
Leg End Member
@Licramite can you answer this question?
Drago
Legendary Member
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- Suburban Poshshire
This is truly excellent news. Just one small thing. Why is there no corresponding decline in serious injury or death rates with helmet use?
classic33
Leg End Member
I got the leg injured, when I was hit, more than any other part.
But at no point did you say "might" or "possibly". You said "does". Which is incorrect.
#3 no, that's not what I said. I said it could break without deforming.
#5 Again, the brain might take damage at 10g, but in other cases it might not. You are wrong to suggest that 10g will in all cases cause brain damage. It is quite possible for the brain to have reduced oxygen for short periods and not suffer any damage. besides, it's not a lack of oxygenation that causes brain injuries in collisions, so the "6g is enough to stop blood getting to the brain" is irrelevant and doesn't apply in the sort of impacts we are talking about.
All of your points you were expressing certainty when none could exist. Which I guess explains why you think helmets protect against head injuries.
Lemond
Senior Member
- Location
- Sunny Suffolk
So, there's no right and no wrong when it comes to helmets. Depending on the circumstances they might protect the wearer from injury, or they might not (and might even make things worse).
Seems fair enough to me. We all make our own choices.
Seems fair enough to me. We all make our own choices.
To start with, because I've read some stuff about it and the arguments for mandatory helmet usage having a negative impact on health at a societal level seem to have some weight to them. Also the risk compensation stuff, which I've never been arsed to go read up on properly, seems like complete common sense to me which is at least as convincing as anyone's "helmets are better for safety - it's just common sense!" arguments 
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