Police getting tougher on speed tolerance

[TheDemonLord]

I agree generally with the focus on accident severity and that a lower impact speed the better the outcome. Much better than the old focus of speed being a primary factor in causing an accident. Around town and in lower speed zones this makes sense.

But, at 80Km/h and above I question how much of a difference it makes especially for a rider. I don't find it credible that the outcome is measurably worse at 110Km/h vrs 100Km/h.

E=1/2mv2

So the energy of a moving object is equal to half of its mass, times its velocity Squared.

So for a 1000 kg object travelling at 27.7 m/s (100 kph) the energy is: 383645 joules
If we now go to 110 kph (30.5 m/s) the energy is: 465125 joules

So yes, a small increase in speed (because the velocity is Squared) does make a difference (5th form physics anyone?) - but the key factor in any crash is how the energy is dissipated and the time over which the deceleration occurs (again, 5th form physics)

[rastuscat]

E=1/2mv2

So the energy of a moving object is equal to half of its mass, times its velocity Squared.

So for a 1000 kg object travelling at 27.7 m/s (100 kph) the energy is: 383645 joules
If we now go to 110 kph (30.5 m/s) the energy is: 465125 joules

So yes, a small increase in speed (because the velocity is Squared) does make a difference (5th form physics anyone?) - but the key factor in any crash is how the energy is dissipated and the time over which the deceleration occurs (again, 5th form physics)

You've fallen into the old trap of believing facts.

Come on, this is KB.

[TheDemonLord]

You've fallen into the old trap of believing facts.

Come on, this is KB.

Heh, Sarcasm aside - it is surprising how many people can't remember basic 5th form Physics

[haydes55]

E=1/2mv2



So the energy of a moving object is equal to half of its mass, times its velocity Squared.



So for a 1000 kg object travelling at 27.7 m/s (100 kph) the energy is: 383645 joules

If we now go to 110 kph (30.5 m/s) the energy is: 465125 joules



So yes, a small increase in speed (because the velocity is Squared) does make a difference (5th form physics anyone?) - but the key factor in any crash is how the energy is dissipated and the time over which the deceleration occurs (again, 5th form physics)

Energy from not crashing in the first place? Sweet fuck all.

[TheDemonLord]

Energy from not crashing in the first place? Sweet fuck all.

That's not how kinetic energy works.............

[Kickaha]

I have heard it said that in Christian countries one third of all suicides occur within the six weeks generally accepted as the Christmas period.

I saw a study two days ago which said that was crap, apparently springtime is the most common time

[rastuscat]

Energy from not crashing in the first place? Sweet fuck all.

Okay, here's a plan. The day after crashes stop happening forever I'll start campaigning to lift all speed limits.

Somehow I can't see my campaign happening any time soon.

Funny, I spend lots of time defending speed enforcement but bugger all time actually doing it. I spend most of my patrol time looking for seatbelts, cellphones, and cases of DLAW.

Driving Like A W***ker.

[BlackSheepLogic]

So yes, a small increase in speed (because the velocity is Squared) does make a difference (5th form physics anyone?) - but the key factor in any crash is how the energy is dissipated and the time over which the deceleration occurs (again, 5th form physics)

Congratulations for remembering 5th form physics. Now factor in survivability of those injuries at 100Km/h vrs 110Km/h. You think I'm any more likely to walk away from the 100Km/h accident than the 110Km/h? What matters at those speeds is how I'm impacted not a few clicks either way.

[BlackSheepLogic]

You've fallen into the old trap of believing facts.
Come on, this is KB.

Yea Rastuscat, lets not factor in the real world outcome to a rider.

[TheDemonLord]

Congratulations for remembering 5th form physics. Now factor in survivability of those injuries at 100Km/h vrs 110Km/h. You think I'm any more likely to walk away from the 100Km/h accident than the 110Km/h? What matters at those speeds is how I'm impacted not a few clicks either way.

Okay.

What determines how you are impacted?

Its the time over which the deceleration occurred (ie did you experience a fatal number of Gs) AND it is how the energy was dissipated. Higher initial energy means that more energy has to be dissipated.

For example (and I am using arbitrary numbers here to prove a point)

Suppose that 500 joules of energy goes gets dissipated by bruising and moderate injuries. Now factor in the 20% extra energy we now have to dissipate by going 10 kph faster - we now have to dissipate 600 joules - which results in broken bones and internal bleeding.

Thats if we go solely down the energy route.

If we do deceleration -

going from 100 kph to 0 in 0.3 seconds gives around 9 G of deceleration, going from 110 kph to 0 in 0.3 seconds is closer to 10 G

For reference - the average G force experianced by a car crashing at 50 kph to 0 is about 15 G - this gives a time elapsed of around 0.08 seconds for a crash

(source is here: http://outreach.phas.ubc.ca/phys420/...danny/info.htm)

if we use 0.08 as the time elapsed for our crash we get 34 G for a crash at 100 kph and 37 G

For reference - Fatal and serious injuries can occur above 25 G, although the human body can withstand peak G forces higher than this for very short periods of time (nanoseconds)

TL;DR - Learn some 5th form Physics - it tells you all about why death is more likely at 110 kph than 100 kph

[buggerit]

Okay.

What determines how you are impacted?

Its the time over which the deceleration occurred (ie did you experience a fatal number of Gs) AND it is how the energy was dissipated. Higher initial energy means that more energy has to be dissipated.

For example (and I am using arbitrary numbers here to prove a point)

Suppose that 500 joules of energy goes gets dissipated by bruising and moderate injuries. Now factor in the 20% extra energy we now have to dissipate by going 10 kph faster - we now have to dissipate 600 joules - which results in broken bones and internal bleeding.

Thats if we go solely down the energy route.

If we do deceleration -

going from 100 kph to 0 in 0.3 seconds gives around 9 G of deceleration, going from 110 kph to 0 in 0.3 seconds is closer to 10 G

For reference - the average G force experianced by a car crashing at 50 kph to 0 is about 15 G - this gives a time elapsed of around 0.08 seconds for a crash

(source is here: http://outreach.phas.ubc.ca/phys420/...danny/info.htm)

if we use 0.08 as the time elapsed for our crash we get 34 G for a crash at 100 kph and 37 G

For reference - Fatal and serious injuries can occur above 25 G, although the human body can withstand peak G forces higher than this for very short periods of time (nanoseconds)

TL;DR - Learn some 5th form Physics - it tells you all about why death is more likely at 110 kph than 100 kph

So going by those figures we are probably fucked at 100kmh anyway?

[BlackSheepLogic]

So going by those figures we are probably fucked at 100kmh anyway?

That was my point since like you I don't live in a text book.

[TheDemonLord]

So going by those figures we are probably fucked at 100kmh anyway?

It depends on the time the deceleration happened over - a head on collision for example happens over a shorter period than say a T-Bone

[TheDemonLord]

That was my point since like you I don't live in a text book.

You may not live in a Text book - but does that mean you are exempt from the laws of Physics?

No?

Thought so.

[BlackSheepLogic]

TL;DR - Learn some 5th form Physics - it tells you all about why death is more likely at 110 kph than 100 kph

Most of us don't live in text books with. At 100Km/h I hit anything head-on my chances of survival are very low as are my chances if I'm run over at 100Km/h. The critical factor is not the speed at that point but how the impact occurs (what I hit, how I hit it, and at what angle I hit it).