Kill a cyclist, get community punishment

I just drive at the speed indicated.

No you don't, you drive at the very limit, there's a big difference.

Again, do you know what limit mean?

@lucas

Just to be clear this graph is in km/h, so if you consider the speeds in miles/hour you may be able to see that even a 1mph difference at makes a significant difference in chances of survival.

BTW it's surprising how much fuel you save driving at 20-25mph compare to 30-35mph, surely that's a great thing to have?

Are you telling me 31 is massively more dangerous than 30. If so you are a fucking idiot.

And 32 isn't massively more dangerous than 31...
And 33 isn't massively more dangerous than 32...
And 34 isn't massively more dangerous than 33...
...
And 85 isn't massively more dangerous than 84...

EDIT: nod to @spiderpie

So why don't we just let everyone drive at whatever speed they think is ok, because of course just being in a car implies that you are perfect at judging what is and isn't safe. All limits are arbitrary, but we have to draw the line somewhere. Again, what is your justification for driving slightly over the limit, and so increasing the danger to everyone, rather than slightly below?

if you think speeding in a moving vehicle is acceptable and perfectly safe, remind me to introduce you to my brother.

They are only allowed to be put in places where there is evidence that excessive speed is causing accidents, well at least that is the case in Hampshire. This is probably because of the perception that they are used as a cash cow.

@lucas

will you actually engage with the points being made or just continue calling anyone who disagrees with you a cunt?

I drive at the very limit in my speed demon of a car which is an EcoFlex Astra ... Christ. If it is a 50 limit, I am doing somewhere between 45 and 50 like everyone else.

Many people are speeding, not keeping to the speed limit.

Have you actually read any of the articles on the links I have posted

http://www.rospa.com/road-safety/advice/drivers/speed/inappropriate/

Who Speeds?5

On 30 mph roads in built-up areas, 45% of car drivers exceed 30 mph and 15% exceed 35 mph.
On 40 mph roads in built-up areas, just over one fifth (21%) of car drivers speed, and 7% go faster than 45 mph.
On single carriageway 60 mph roads in non-built-up areas, 7% of drivers speed but only 1% go over 70 mph
On 70 mph dual carriageways in non-built-up areas, over one third of car drivers (37%) exceed the speed limit, with 10% of those going over 80 mph.
On motorways in non-built-up areas with 70 mph limits, almost half (46%) of car drivers exceed the speed limit, with 11% going faster than 80 mph.

Don't make strawman arguments and misrepresent what I said.

You keep avoiding the issues raised and just insulting people.

Half m v squared

1/2 * mass * velocity squared.

This means for every single increase of speed the difference is squared massively increasing the kinetic energy carried by the moving vehicle. Yes it makes a fucking massive difference.

I indicated that by saying "I think it is arbitrary"

Actually you said that it IS arbitrary.

The point is that the limits are what they are for a reason, regardless of whether you understand why, and regardless of whether you care to find out the reasons why.

You claim to drive within the speed limit, yet believe them to be arbitrary, doesn't this suggest that you might sympathise with someone who's been caught by the police driving 5mph over the limit? What about someone who's killed someone who might otherwise have survived had they driven 5mph slower? Do you sympathise with the driver, or do you throw the book at them for having driven above the limit, a limit which you believe is arbitrary?

Don't make strawman arguments and misrepresent what I said.

Since I can't see which of my posts you're referring to, that's not massively helpful.

Mate - give up. I don't know what your angle is here or who you're trying to defend but I don't think a thread on a cycling forum about drivers negligently killing cyclists is the place to do it.

Shouldn't there be speed limits where excessive speed increases the possibility of somebody being killed or seriously injured in the event of an accident?

Half m v squared

1/2 * mass * velocity squared.

This means for every single increase of speed the difference is squared massively increasing the kinetic energy carried by the moving vehicle. Yes it makes a fucking massive difference.

Is it the v-squared part of the kinetic energy that makes the difference? Given the relative difference in mass between a pedestrian and a car isn't the pedestrian (or at least parts of their body) just accelerated, more or less instantaneously, up to the speed of the car when they're struck? Presumably it's this instantaneous acceleration and then deceleration when they then hit the road that does the damage.

You claim to drive within the speed limit, yet believe them to be arbitrary, doesn't this suggest that you might sympathise with someone who's been caught by the police driving 5mph over the limit?

Yes, but that doesn't mean there is some massive conspiracy happening in a jury.

I do remember my A-level physics, however you are assuming that the driver won't be decelerating and that 100% of all the energy will be transferred (it won't).

This cyclist fatality is relevant I think.

https://www.lfgss.com/conversations/252761/

The cyclist was under the influence and somehow lost control of his bike however if the driver of the car had been observing the speed limit he very likely would have had time to stop his car without hitting the cyclist.

No I am specifically ignoring you, because you made the comment to try to exclude me from the conversation.

Lumping a diverse group of people into some guilty other won't make you any friends which was my point like about 2 pages ago on here.

Yes because E is proportional to the square of the velocity.

MG's point is that the KE is proportional to the square of the velocity.

But yes, a vehicle with more mass will also have more KE, but in direct proportion.

Both the mass and velocity make a difference but if you were to double the mass, the kinetic energy would also double.
Double the velocity and energy goes up squared.

m = 5
v = 5
E = 0.5 * 5 * 5^2 = 62.5 Joules

m = 6
v = 5
E = 0.5 * 6 * 5^2 = 75 joules

m = 5
v = 6
E = 0.5 * 5 * 6^2 = 90 joules

increases in mass = linear increase in energy.
increases in velocity ≠ linear increase in energy.

Yes because E is proportional to the square of the velocity.

I understand the equation, I'm just not sure it's relevant. If you're hit by a vehicle at 40mph then you will very rapidly be accelerated up to 40mph regardless of whether it's a car, van, or HGV because they are all much heavier than you and so none of them will be slowed down appreciably due to conservation of momentum.

In any case this isn't relevant, since we have the direct measurements of the relationship of impact speed on probability of fatality that @dancing james posted.