Police get riders at over 200 km/h

[merv]

I blame it all on the South Island, it makes bikers ride fast like that, its not their fault, the Police should make allowance for that.

Is it something to do with the Island really being a fish and trying to race hard away from Maui or something?

[Butch]

Its coz the air is cooler down here and we all know bike produce more power easier with a colder air flow....

[slofox]

Well, it's SOUTH innit? Which is DOWN innit? So ya go faster going DOWN dontcha?...fuckin obvious I woulda thort...

[3umph]

Its coz the air is cooler down here and we all know bike produce more power easier with a colder air flow....

Well, it's SOUTH innit? Which is DOWN innit? So ya go faster going DOWN dontcha?...fuckin obvious I woulda thort...

yip yip yip

[Forest]

I can assure you that no kinetic energy is being imparted into the other body during a collision. What you are saying is equivalent to the other body speeding up during the impact - that would emply a negative mass if that should make sense physically.

Are you serious?

Have you never played billiards?

Each colliding body imparts energy into the other. In the case of billiard balls, the collisions are almost entirely elastic. Stop and think about it for a moment.

So what you are saying is: "more kinetic energy = more energetic collision". How profound.

Again, you are mistaken - or at the very least guilty of over-simplificating the matter.

Right. That's exactly what I am saying.

Traveling at higher speeds results in more energetic collisions. The energy of the moving bodies is proportional to the square of the velocities. Therefore traveling at higher speeds will have an exponentially adverse effect on the unfortunate person that you collide with.

[Forest]

Wow, This is great news. If you are correct I can ride my suzu 1000 at high speed into a concrete wall and not only will the bike remain undamaged, but I'll suffer no injuries at all because all that kinetic energy will transferred into the wall.

The amount of damage to the wall will increase as your speed increases.

Do you disagree with this?

Somehow I don't think I'll risk it. I'll continue to believe in conservation of momentum, and energy being disapated into both bodies according to function of force x distance. As the wall wont move, then all the energy would be disapated with my own body and the bike. That seems both painful and expensive and lines up with what we know to happen in practice.

Yes. Energy is dissipated into both bodies!!

And that is the problem with vehicle collisions. Higher speeds results in exponentially more energetic collisions.

[yachtie10]

I blame it all on the South Island, it makes bikers ride fast like that, its not their fault, the Police should make allowance for that.

Is it something to do with the Island really being a fish and trying to race hard away from Maui or something?

cool excuse except the north islands the fish, south islands the canoe

[Highlander]

cool excuse except the north islands the fish, south islands the canoe

Yup, Wellington is the mouth, East Cape / Taranaki the fins and Auckland.....

[Mikkel]

Each colliding body imparts energy into the other. In the case of billiard balls, the collisions are almost entirely elastic. Stop and think about it for a moment.

It's momentum. The fact that they are almost perfectly elastic collisions means that in that particular case you can actually use conservation of energy to gain useful information.

In an impact where there is deformation this is not true. In such imperfect circumstances you consider the momentum first because the kinetic energy is not conserved - some of it will be transformed into heat and deformation during the impact. On the other hand conservation of momentum will allow you to figure out the velocities after the impact and you can then calculate the kinetic energies associated with each body.

Right. That's exactly what I am saying.

Traveling at higher speeds results in more energetic collisions. The energy of the moving bodies is proportional to the square of the velocities. Therefore traveling at higher speeds will have an exponentially adverse effect on the unfortunate person that you collide with.

Your statements (equations even):

"higher kinetic energy = bigger collision"
&
"bigger = more energetic"

=> "higher kinetic energy = more energetic collision"

Of course that is correct - but it just doesn't contain any insights at all. It's no different from saying that "colder = lower temperature" i.e. obvious and uninteresting.

The fact of the matter is that the severity of an impact is closely related to the forces acting upon your body during the impact which again is the time derivative of change of momentum.

Also, the kinetic energy is not growing exponentially with the velocity by the way - it's a quadratic growth... not to be pedantic or anything.

[Winston001]

Fascinating physics discussion - suspect you chaps are reading past each other and really arguing definitions.

So - any update on what's happening with these lads? Charges?

[Squid]

I blame it all on the South Island, it makes bikers ride fast like that, its not their fault, the Police should make allowance for that.

Is it something to do with the Island really being a fish and trying to race hard away from Maui or something?

Its coz the air is cooler down here and we all know bike produce more power easier with a colder air flow....

Well, it's SOUTH innit? Which is DOWN innit? So ya go faster going DOWN dontcha?...fuckin obvious I woulda thort...

As a recent convict, no CONVERT to the south island I feel oddly qualifed to answer some of these questions
- YES it is colder down here,
- YES my gixxa likes it better,
- YES it is easier to go faster, dunno if that coz of the downhill aspect of the fact everthing is just that much futher away and takes longer to get there... Like riding along towards a set of mountains and thinking "yeah about a hr away" 2 hours later...... @ 100kph that is.

Yup, Wellington is the mouth, East Cape / Taranaki the fins and Auckland.....

Aucklands the arse. It has to be, its auckland after all..

Fascinating physics discussion - suspect you chaps are reading past each other and really arguing definitions.

So - any update on what's happening with these lads? Charges?

Have been keeping a eye on the local papers but havnt heard anything more about it.

[Monty69]

Wow science lessons on KB, good reading so far. Well done for getting busted at 211kmh mystery bikers, and nice self control stopping for the cops! good story to tell your mates I took... i mean a friend took my new CBR up to 250kmh on an empty stretch of road with no driveways or intersections and plenty of clear visibility all round on the weekend and i feel that was safe, even on a public road.

[Jantar]

The amount of damage to the wall will increase as your speed increases.

Do you disagree with this?

Yes I do disagree. In many cases there would be no damage to the wall at all. A very sensitive thermocouple inside the concrete may register a slight rise in temperature showing a small amount of energy transfer, but certainly not ALL the energy as you claimed in an earlier post.

Yes. Energy is dissipated into both bodies!!

And that is the problem with vehicle collisions. Higher speeds results in exponentially more energetic collisions.

This part I almost entirely agree with. However as Mikkel has already pointed out the total energy rises with the square of the speed, noit exponetially, but it is the time that the energy is dissipated, and the rate of dissipation that determines the amount of injury/damage etc.

So come off your bike at over 200 kmh onto a damp grass surface where you can slide for a long distance and you are likely to suffer no injury at all. (Yes I have done this at Levels). Hit something solid, like another vehicle, at the same speed and injury is certain.

[Winston001]

Yes I do disagree. In many cases there would be no damage to the wall at all. A very sensitive thermocouple inside the concrete may register a slight rise in temperature showing a small amount of energy transfer, but certainly not ALL the energy as you claimed in an earlier post.



This part I almost entirely agree with. However as Mikkel has already pointed out the total energy rises with the square of the speed, noit exponetially, but it is the time that the energy is dissipated, and the rate of dissipation that determines the amount of injury/damage etc.

So come off your bike at over 200 kmh onto a damp grass surface where you can slide for a long distance and you are likely to suffer no injury at all. (Yes I have done this at Levels). Hit something solid, like another vehicle, at the same speed and injury is certain.

Haven't followed the argument but seems like you guys just need to remember e=mc2. The faster the mass is moving, the greater the energy of the body. At lightspeed, pure energy only, all mass is converted.

At somewhat more pedestrian speeds, energy of any collision will be transferred in numerous directions - the brick wall's atoms will vibrate more quickly, as will the bikes atoms, and the air will be affected, there will be photon releases, and sonic energy. Crunch. Heck even the local gravity field will flinch and the local magnetic field will be interrupted by bits of flying iron disrupting its flow.

[Edbear]

...

So come off your bike at over 200 kmh onto a damp grass surface where you can slide for a long distance and you are likely to suffer no injury at all. (Yes I have done this at Levels). Hit something solid, like another vehicle, at the same speed and injury is certain.

I coulda told ya that without the Physics lesson...

...At lightspeed, pure energy only, all mass is converted. ...

Can you put that in Physics?
http://www.thekeyboard.org.uk/Faster...ht%20speed.htm