R1200GSA LC v Jaguar XF

[Engineer]

A few thoughts.

It is not a sharp bend
He was not over the line as he entered the bend
There was significant surface water clearly seen from the cars perspective but maybe not from the other way.
Apparent speed is exaggerated by the camera view
Combined speed of the 2 vehicles makes it look fast - impact speed of at least 70mph thus triggering airbags etc..
The surface water mentioned already upset the stability of the bike

It is easy to be judgemental but we do not know all the facts and maybe should not be so quick to make judgements.

That said, too many drivers (4 & 2 wheels)round here seem unable to negotiate a right hand bend without crossing the centre line....

Just a small point of order - the impact speed is not the speed of both vehicles added together - if you come to a dead stop in a head-on it is the same as hitting a brick wall at your travelling speed, the speed of the other vehicle is irrelevant (physics innit) The approach speed is 70mph, the impact speed is 35mph.

 

[Beemerman59]

Just a small point of order - the impact speed is not the speed of both vehicles added together - if you come to a dead stop in a head-on it is the same as hitting a brick wall at your travelling speed, the speed of the other vehicle is irrelevant (physics innit) The approach speed is 70mph, the impact speed is 35mph.

Excuse my lack of understanding - if the brick wall was travelling at 35 miles an hour, are you saying the impact would be no worse than if the brick wall was stationary?

 

[Nice 'n' Fat]

We need an Engineer to pass comment on this

 

[Rushy]

It is easy to be judgemental but we do not know all the facts and maybe should not be so quick to make judgements.

That said, too many drivers (4 & 2 wheels)round here seem unable to negotiate a right hand bend without crossing the centre line....

Agreed.

Also its amazing how many drivers cannot negotiate a medium or tight right hand bend without cutting the corner and entering on to the wrong side of the road. Even when travelling at a moderate to slow speed they don't seem confident/skilled enough to run deep into the bend before turning (They turn in far too early) and also don't use the power to pull the car round the bend.
Lots of poorly skilled drivers out there . I do wish they would make some sort of advanced driving compulsory within 12 mths of passing test rather then keep on reducing speed limits.....dreaming I know

 

[POL382]

Just a small point of order - the impact speed is not the speed of both vehicles added together - if you come to a dead stop in a head-on it is the same as hitting a brick wall at your travelling speed, the speed of the other vehicle is irrelevant (physics innit) The approach speed is 70mph, the impact speed is 35mph.

If both vehicles were the same mass and speed at the point of impact then both vehicles would stop dead, however there was a big difference in the mass of these two vehicles.

 

[Beemerman59]

We need an Engineer to pass comment on this

Is there one on this site?

 

[Humbug]

Haha............he's got a bit to learn then, Andy

We all know that's the new hip and tendy buzzword, around here.............'spirited riding'.....

They usually end up in a ditch or hedge. Sometimes they hit a car. It's inevitable John.

 

[Stevemoid]

A quick google search says:

"I was watching a youtube video the other day where an economist said that he challenged his physics professor on this question back when he was in school. His professor said each scenario is the same, while he said that they are different, and he said he supplied a proof showing otherwise.

He didn't say whether or not the cars are the same mass, but I assumed they were. To state it more clearly, in the first instance each car is traveling at 50mph in the opposite direction and they collide with each other. In the second scenario, a car travels at 100 mph and crashes into a brick wall. Which one is "worse"?

When I first heard it, I thought, "of course they're the same!" But then I took a step back and thought about it again. It seems like in the first scenario the total energy of the system is the KE of the two cars, or 12mv2+12mv2=mv212mv2+12mv2=mv2. In the second scenario, it's the KE of the car plus wall, which is 12m(2v)2+0=2mv212m(2v)2+0=2mv2. So the car crashing into the wall has to absorb (and dissipate via heat) twice as much energy, so crashing into the wall is in fact worse."


http://physics.stackexchange.com/questions/45578/is-two-cars-colliding-at-50mph-the-same-as-one-car-colliding-into-a-wall-at-100


The answer directly below the point above goes into more detail still.

 

[Beemerman59]

A quick google search says:

"I was watching a youtube video the other day where an economist said that he challenged his physics professor on this question back when he was in school. His professor said each scenario is the same, while he said that they are different, and he said he supplied a proof showing otherwise.

He didn't say whether or not the cars are the same mass, but I assumed they were. To state it more clearly, in the first instance each car is traveling at 50mph in the opposite direction and they collide with each other. In the second scenario, a car travels at 100 mph and crashes into a brick wall. Which one is "worse"?

When I first heard it, I thought, "of course they're the same!" But then I took a step back and thought about it again. It seems like in the first scenario the total energy of the system is the KE of the two cars, or 12mv2+12mv2=mv212mv2+12mv2=mv2. In the second scenario, it's the KE of the car plus wall, which is 12m(2v)2+0=2mv212m(2v)2+0=2mv2. So the car crashing into the wall has to absorb (and dissipate via heat) twice as much energy, so crashing into the wall is in fact worse."


http://physics.stackexchange.com/questions/45578/is-two-cars-colliding-at-50mph-the-same-as-one-car-colliding-into-a-wall-at-100


The answer directly below the point above goes into more detail still.

Impressive numbers but alas I'm still confused how two vehicles having a head on, both doing 35mph, have according to Engineer, an impact speed of only 35mph?

 

[Ethaneil]

Thanks for the condescending quote.

Do you really think its an aspiration to be on your own side of the road, on a blind corner, with double white lines? Surely not.

Apologies Jbiker, wasn't meant to be condescending towards you, I agree with you. The riders positioning looks bad, but we don't know why. There just may be a good reason.

I didn't clock your name when i referenced JB, my apologies again, no offence intended at all.

I was referring to The Lord on High, johnnyboxer, riding God, and bell end!

 

[Nutty]

I was referring to The Lord on High, johnnyboxer, riding God, and bell end!

 

[J biker]

^^^^^ forums eh...how to take things the wrong way and take insult.

Still, very easy to pass judgement based on a short video clip. All speculation without facts.

 

[Ozz]

Two identical cars weighing 2000kg each are travelling at exactly 25 miles per hour and collide dead centre, head on. The closing speed of the vehicles is 50mph. The force each car receives from the impact is the same.

Each car imparts a force in an amount equivalent to its weight (mass) times its speed. If one car travelling at 25 mph hit a concrete wall it would generate 50,000kg of force (F=MV).
The two cars in the above example together generate 100,000kg of force in a head on collision. Since each car is identical and the speed is the same, each car would impart 50,000kg of force to the other car, exactly the same as colliding with the stationary wall at 25 mph.

In order for both of them to receive an amount of force equivalent to travelling 50 mph there needs to be an additional 100,000kg of force.

Assuming that the bike is doing 40mph and the car is doing 35 mph the closing speed of the two vehicles is 75mph. The collision speed of each vehicles put simply is Bike - 40mph and the car 35mph. Where it is complicated is that the two vehicles have differing masses and the collision was not head on but glancing.

The bike weighs 260kg wet plus 100kg rider @ 40mph = 14,400kg of force.
The car weighs 1545kg plus 70kg fuel and 100kg driver @ 35mph = 60,025kg of force.

At this point my maths skills run out...

 

[andylel]

The bike weighs 260kg wet plus 100kg rider @ 40mph = 14,400kg of force.

At this point my maths skills run out...

You have much more maths skill than me but at a practical level surely the rider weight is irrelevant to the calculation as the rider is not connected to the bike and would continue in the same direction at the same speed until other forces acted on him / her.

Can't even believe I wrote this but convalescence does strange things to ones mind.

 

[jimbo]

Two identical cars weighing 2000kg each are travelling at exactly 25 miles per hour and collide dead centre, head on. The closing speed of the vehicles is 50mph. The force each car receives from the impact is the same.

Each car imparts a force in an amount equivalent to its weight (mass) times its speed. If one car travelling at 25 mph hit a concrete wall it would generate 50,000kg of force (F=MV).
The two cars in the above example together generate 100,000kg of force in a head on collision. Since each car is identical and the speed is the same, each car would impart 50,000kg of force to the other car, exactly the same as colliding with the stationary wall at 25 mph.

In order for both of them to receive an amount of force equivalent to travelling 50 mph there needs to be an additional 100,000kg of force.

Assuming that the bike is doing 40mph and the car is doing 35 mph the closing speed of the two vehicles is 75mph. The collision speed of each vehicles put simply is Bike - 40mph and the car 35mph. Where it is complicated is that the two vehicles have differing masses and the collision was not head on but glancing.

The bike weighs 260kg wet plus 100kg rider @ 40mph = 14,400kg of force.
The car weighs 1545kg plus 70kg fuel and 100kg driver @ 35mph = 60,025kg of force.

At this point my maths skills run out...

Cars have crumple zones engineered to absorb energy without intruding into the interior and reducing the acceleration felt by the occupants. Bikes, Don't.

 

[JohnnyBoxer]

I was referring to The Lord on High, johnnyboxer, riding God, and bell end!

Fuck off you fucking knob end

I am no riding god, far from it

However I do usually stick to my carriageway and refrain from straying into oncoming cars & hitting them head on

I won't change my view that the GSA rider was 100% to blame

His riding was appalling on that piece of road

He needs prosecuting for dangerous driving at the very least

Defending his riding is delusional - he made no attempt to correct his position at all

How would you feel if your wife/daughter/husband was driving the Jag?

Get a fucking grip Tosser

 

[JohnnyBoxer]

You can fucking shut up too with your 'spirited riding'

He was probably following you and couldn't keep up

 

[BillWright]

Hi

So much bollocks on this thread, I mean what Tosser weighs just 100kgs

 

[Nice 'n' Fat]

The pies in my panniers weigh more than that

 

[Blackal]

Fuck off you fucking knob end

I am no riding god, far from it

However I do usually stick to my carriageway and refrain from straying into oncoming cars & hitting them head on

I won't change my view that the GSA rider was 100% to blame

His riding was appalling on that piece of road

He needs prosecuting for dangerous driving at the very least

Defending his riding is delusional - he made no attempt to correct his position at all

How would you feel if your wife/daughter/husband was driving the Jag?

Get a fucking grip Tosser

Right - on all points.........


Al