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Crashed Minis - Safety related


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#166 Black.Ghost

Black.Ghost

    Formerly known as TneMini.

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Posted 01 September 2011 - 03:12 PM

I know this is an old thread but I do have a couple of points, I apologise for dragging up old stuff.

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I think it also helps safty wise knowing the limits, like when you first go round a roundabout in the wet too fast, or your first lose the backend by countersteering too fast, thats why personally, i dont believe theres any harm in doing harndbrakes turns on a empty car park when you first pass your test, or messiong around in the snow and ice in your car in an open space, because you learn how to control it when your rear end swings out,

But your all bound to dissagree, I just think not enough people know what to do in situations where they loose control off there car or loose traction, because theyve been taught to pass there test and thats it.



I dont dissagree with what your saying, infact i plan to learn car controll in a similar way when i get my liecence, I feel that the government should change the test to include car controll on a higher level.

The ironic thing is that the people who do go out to car parks and open spaces to do handbrake turns and donuts, can end up with a fine, or points on there liecence! and they are the drivers that will be the safer drivers on the road.

Its the nanny state i tells ya!

It would mean that there would be far less accidents and induries due to accidents, because all the new drivers would have to know how to controll the car before they are given a liecence.
If they included things like skid pan driving, drifting, track driving in the lessons and test, everyone would be a better drivers, but the test would be more expensive, and they would need to open more specialist centres, which the government would claim it costs too much.

Would you pay more to get a liecence, if you knew that the extra money you are spending on the car controll could save you life? I would!

In principal, this is great. In practice, the majority *NOT ALL*, but the majority are the boy racers who aren't going to be the safest drivers anyway. So I completely disagree with this and I think the police are perfectly right in dishing out points.

If you want to practice stuff like this, there are places you can go. I do agree more car control needs to be taught during lessons.

No action had been taken to the mini at this stage as it was obvious that the driver was dead. all the damage you see was due to an estimated 80mph impact speed (40mph each vehicle)



That is very misleading. The total energy in this crash was 1/4 of the energy in an 80 mph crash:

Emini = 1/2 x mass x V^2
Ecar = 1/2 x mass x V^2

40 x 40 + 40 x 40 < 80 x 80

40 x 40 + 40 x 40 = 1/4 x 80 x 80

That is an important point because an 80mph crash is significantly worse than this crash. Also this was effectively just a 40 mph and people should understand this is the effect of just a 40mph crash (and consider the danger that this speed poses as opposed to thinking thats what happens at 80 so 40 is OK)...

If the mathematics dont make sense to you consider it this way. Where the two cars meet imagine a solid wall. Therefore both cars just come to a halt at this wall like they do if they hit each other. It is now clear it doesn't matter that there was another car involved as it is now just a 40mph crash into something totally solid. I would much prefer you gave that message to people than this was an 80mph crash. That was a 40mph crash only. However it gets worse for the poor mini driver...

Due to the principle of conservation of momentum you can prove the mini suffers more than the other car as it is lighter - it will take more of the impact than the heavier car (and conversely the heavier car has to absorb less energy). Again for this to make sense without the maths look at it this way. The lighter mini will end up accelerating in the direction of the heavier car hence its impact speed is say 40mph plus the speed it ends up doing after the impact in the opposite direction whereas the heavy car's impact speed is 40 minus the speed it still continues with after the impact.

This is one reason why I particularly dislike the 'SUVs are safe message' people like to give out. They are safe for the selfish driver inside one but considerably more unsafe for everyone else. In fact all that weight just adds more energy into a crash which doesn't need to be there.

I'm not sure I entirely agree with this. In the first equations, the mass has been completely ignored, which is quite significant because of the Mini being so comparatively small and light. So if assume the Mini weighs 0.65 tonnes and the other car weighs 1.6 tonnes, we have (0.5 x 0.65 x 40 x 40) + (0.5 x 1.6 x 40 x 40) = 520 + 1280 = 1800. Now if we use that and work backwards to find a weight, we know that 1800 = 0.5 x weight x 80 x 80, so 1800 = 3200 x weight therefore the weight = 0.56 tonnes, which is not too unreasonable to assume for a lightened Mini. So the impact is equivalent to that for a lightened Mini at 80mph.

Also using the above maths, if we take the 1800 figure as the total energy, we can then work out that 1800 = 0.5 x mass x v^2. If we know the mass to be 0.65 for the mini, we can calculate that 1800 = 0.5 x 0.65 x v^2, so 1800/0.325 = v^2. so v^2 = 5538.46154 (I did use a calculator to save time) and therefore the speed is 74.5 mph approx. Therefore this is not a 40 mph accident.

I understand your point about conservation of momentum, and that the Mini would take more of the brunt - the other car has more momentum and the comparatively tiny Mini has more work to do to stop the car - in reality it wouldn't stop the car and would bounce back.

Its very important to remember that the angle of impact and size of the impact area is very important. Angles result in cars bouncing off at different angles, often causing slightly less damage. In addition, in an impact, if it is spread over a larger physical area it will be dispersed more and again cause different damage than the same energy impacting a very small area.

So while this might not be an 80 mph crash, its not far off. Its not the same as hitting a wall at 40. You have to remember energy cannot be lost or created, just transferred to a different type. Therefore hitting a stationary object cannot possibly be the same as hitting something that is moving.

Note - it has been 10 years since I studied Maths and 12 since Physics, so if anything is wrong I apologise, but I am using the same equations used previously. Also




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