Crash on Waterloo Quadrant/Princes St (12 March)

[ital916]

'Tis the last time you ever get any of our nachoes then.

Ahh but I do contribute with pizza, and deep fried choch bars and I have fed andrew more than his own family :P. Plus I contribute to movies like this friday, ill bring some badass movies, plus I bring beer etc etc.

[ehab2weelr]

pic of the crash........

[shingo]

Is it just me or does it look like the bike impacted the car from the right hand side (i.e. next to the driver) and not headon, judging from the direction of crumple.

Dear god man. Remind me never to go anywhere near anything you design or build.

[PirateJafa]

Is it just me or does it look like the bike impacted the car from the right hand side (i.e. next to the driver) and not headon, judging from the direction of crumple.

:slap: Considering that the forks appear to be bent out to the left, it was probably caused by, oh, I don't know, a accident similar to the description given? :slap:

[ital916]

Dear god man. Remind me never to go anywhere near anything you design or build.

I meant down the drivers side, near the front as in i.e. it wasnt a direct head on. My browser was displaying only a thumbnail of it the size it is shown in the thread. Hence I really cant tell what the car is like in the pic.

[aewilliam]

Met the fulla once, good dude. Wouldve been keen to do so again and chill on a motorised saddle-type vehicle ride in near future...guess not to be. Sucky esp for one who has doen tso for much of his years! Hope you heal up dude...maybe you can chillax at one of the many o'seas places you are able to go to while you rest up...

And with this thread...you uni students - wheres my taxpayers $$$ going to?!

Would be wishing one of ya uni students may have thrown on some fancy physics calcs with what info/hearsay (distance from impact being the 'known' variable) we have already and put to rest some of the speculation floating around...i for one left them sciences behind in Form 7 (yup, THAT long ago, before it was called Year 13).

Laws of Physics aside...what about traffic laws - Thought velocity of oncoming vehicle with green light (on-comer) would not stop the fact that the right-turning vehicle without green light (obstructer) didnt give way to on-comer, and so obstructer is immediately in wrong?

In my mind, i thought velocity did not cause the incident but rather the presence of the vehicle obstructing oncoming traffic - Thereagain, one could say that if the velocity of the on-comer was far lower, then the potential obstructer would have safely passed through.

Does anone know what the laws behind this are, if in a hypothetical incident two laws are broken in the lead-up to the incident?

[Ragingrob]

Definitely a decent head on collision there. Bugger! And looks like the car was off-centre too, as in turning right.

But yeah we don't know about the speed or riding behaviour. If the bike was going well above 50kph then the car may have started turning before the bike was even in sight. The bike could've darted out from behind one of the cars turning left and shot out into the intersection, once again the car wouldn't have seen him till it was too late. Bike may have left his left indicator on and car thought he was turning so had right of way.

On the other hand, yes the car could've simply turned right in front of the bike.

Did someone say that there were no skidmarks from either party? That's odd!

[zzzbang]

When in doubt, power out?

[Real_Wolf]

Using basic physics we can shove some 'variables' into this stuff and see what the time of reaction could have been
The time to react, assuming from the bikes perspective the car could only be seen once it left the hill, which is approximately, for a large estimate of 40 meters:

Now, we assume 80km/h and we have a 22.2 m/s, meaning about 1.8 seconds to react (remember, 80km/h is the relative velocity, not the velocity of one of them).

If we chuck that doen to say 50km/h (one travelling at 25, other at 25), and the reaction time is about 2.9 seconds.

Chuck it up to a large estimate of 120km/h, meaning both at 60km/h, and you get 1.2 seconds reaction time.

Looking at that, if we assume a sight line of 40 meters, 2.9 seconds is quite a long time, count it out to yourself or watch a clock. It would definetely have some skidmarks from one of them, plenty of time to break, so its safe to assume that one of them was travelling at a speed that was at least 40-50km/h. Looking at it, 1.8 seconds is long enough that no skidmarks is unusual too, however it is possible that both people froze in that amount of time, but unlikely. That means a speed of about 50 and 30 is possible but one or both were probably travelling faster. 1.2 seconds sounds like a fast enough crash that assuming that your foot/hand wasn't over the brake, you would not be able to react and touch it in time to get any skid marks, which would lead to that lack.


There, that enough smart-ass-ery for you? I will note, in these calculations, I'm bloody awful at estimating, so the 'distance' of sight, and the 'approximate speeds' and the 'how long to react' are all judged on what I would assume to be the case in this situation, such as a rider/driver who is not FULLY aware and expecting a crash, the sort of person you normally see on the road, paying attention but not looking for the unexpected.

[ehab2weelr]

im a biology student numbers mean nothing to me.....what the hell were you on a bout???? hahah
give me some stats and il be happy.

[aewilliam]

dargh...so confusing...physics looked much simpler 8 years ago! was hoping forsome sorta projectile-based calculation with fewer assumptions...

Found something online for horizontal projectiles...
does Height=.5*a*T^2 sound familiar?
using this, 'a' being gravity of 9.8 progresses to
Height=.5*9.8*(d/v)^2
...a height of 800mm for 735mm cbr250 seat height +some leg extension for initial height...

brings it to around 70kmh velocity, assumedly combined...

I have noisly locked up car wheels and not left any road-marks from around 30kmh, so would think anything below this woudlnt leave marks from car. suggesting rider was travelling at 50kmh upon impact with NO BRAKING hence no skid mark, leaving 20kmh (assuming car was moving considering its off-centre road position) for car to also brake with no skid mark...

Would this go anywhere in defending bike rider's reasonable (close to posted speed-limit) velocity?

[Real_Wolf]

um, unless you mean that he was accelerating with no initial velocity, that equation means nothing. And since your using gravity, the acceleration would be downwards. Yeah, your equation means nothing.

[aewilliam]

um, unless you mean that he was accelerating with no initial velocity, that equation means nothing. And since your using gravity, the acceleration would be downwards. Yeah, your equation means nothing.

Height=.5*9.8*(d/v)^2
...a height of 800mm for 735mm cbr250 seat height +some leg extension for initial height...

Would this go anywhere in defending bike rider's reasonable (close to posted speed-limit) velocity?

After impact, my assumption would be that there would be no more acceleration on the riders airborne body (projectile) except gravity?

And im not assuming no initial velocity...initial velocity is my UNKNOWN variable? Or can assume an initial (combined?) velocity of 70kmh or 19.5m/s to match the distance to landing of projectile...

Height=.5*9.8*(d/v)^2
.8 = .5*9.8*(d/19.5)^2
.8/(.5*9.8)=(d/19.5)^2
sqrt(0.1633) = d/19.5
19.5*sqrt(0.1633) = d
= 8.02m
+ 2m of sliding = 10m from impact?

Or am I just using an incorrect equation or misunderstanding?

[Real_Wolf]

you do realise that you can't use a time in that function with it working.

Not to mention that your trying to turn the problem into one dimension with that equation, and your still missing out the initial velocity. So what it says there is the change in height is equal to the acceleration times the time. Thats rather obvious. But thats vertical acceleration, and the time would be a distance in the vertical direction.

You haev to keep the same axis if you want to do an equation as you have, and since yoru using "height" then all your velocities, initial and final, and your acceleration, must be in the said direction.

Not to mention you can't substitute d/v for time, because the velocity is not a constant, and neither is the distance, nor do they have relevance

[aewilliam]

knew physics couldnt be that simple...
Oh well, churrs DW, guess I will just stick to trying not to be a projectile! same goes for the rest of y'all

Yo ehab, Any word on how our pelvically-limited breh is doing? I guess the light-weight of a blow-up doll is all his pelvis will be able to support for the next very long time. Or either of his hands, which sound to be undamaged... extra blood flowing to the region may help the healing process?