fucking hang-gliders

disoriented wrote:

dicks-naughty-account wrote:I think all this "stopping distance" stuff is a little crap. it's all tested in perfect conditions, and the riders doing the testing have time to prepare their stop perfectly and shit. when you're thundering along you don't really anticipate a car blocking the road in such a retarded place. I doubt you could pull off the perfect stop like the figures suggest while getting the biggest, bad ass fright of your goddamn life and saying "holy cow man wtf is that doing there".

The motor bike rider was a champion racer it would be hard to belive he could stop a motorbike quickly.

I could use 0.75 seconds instead of 1 second for reaction time and it will still have the same results. In fact you will find that instead of stopping 3m short of the cop at 100kph they would stop 10m before the cop, and at 150kph they would still be doing over 100kph when they hit the cop car.

Now lets say cop the cop was lieing about the distance between them and the brow of the hill? so lets say it was 60m instead of 70m at 100kph the bike would be doing only about 25 kph when they hit the cop. If it was 50m instead of 70m at 100kph the bike would be doing about 50kph, which in my experence with crashing bicycles at that speed it will hurt but you will live and most likely walk away from it.

I can explain it all in a really long scientificly(sp) post if you like with all the numbers and formula explaining it all

yes please.

disoriented wrote:

dicks-naughty-account wrote:I think all this "stopping distance" stuff is a little crap. it's all tested in perfect conditions, and the riders doing the testing have time to prepare their stop perfectly and shit. when you're thundering along you don't really anticipate a car blocking the road in such a retarded place. I doubt you could pull off the perfect stop like the figures suggest while getting the biggest, bad ass fright of your goddamn life and saying "holy cow man wtf is that doing there".

The motor bike rider was a champion racer it would be hard to belive he could stop a motorbike quickly.

I could use 0.75 seconds instead of 1 second for reaction time and it will still have the same results. In fact you will find that instead of stopping 3m short of the cop at 100kph they would stop 10m before the cop, and at 150kph they would still be doing over 100kph when they hit the cop car.

Now lets say cop the cop was lieing about the distance between them and the brow of the hill? so lets say it was 60m instead of 70m at 100kph the bike would be doing only about 25 kph when they hit the cop. If it was 50m instead of 70m at 100kph the bike would be doing about 50kph, which in my experence with crashing bicycles at that speed it will hurt but you will live and most likely walk away from it.

I can explain it all in a really long scientificly(sp) post if you like with all the numbers and formula explaining it all

This is interesting stuff. What is your background ?

schlek1 wrote:

disoriented wrote:

dicks-naughty-account wrote:I think all this "stopping distance" stuff is a little crap. it's all tested in perfect conditions, and the riders doing the testing have time to prepare their stop perfectly and shit. when you're thundering along you don't really anticipate a car blocking the road in such a retarded place. I doubt you could pull off the perfect stop like the figures suggest while getting the biggest, bad ass fright of your goddamn life and saying "holy cow man wtf is that doing there".

The motor bike rider was a champion racer it would be hard to belive he could stop a motorbike quickly.

I could use 0.75 seconds instead of 1 second for reaction time and it will still have the same results. In fact you will find that instead of stopping 3m short of the cop at 100kph they would stop 10m before the cop, and at 150kph they would still be doing over 100kph when they hit the cop car.

Now lets say cop the cop was lieing about the distance between them and the brow of the hill? so lets say it was 60m instead of 70m at 100kph the bike would be doing only about 25 kph when they hit the cop. If it was 50m instead of 70m at 100kph the bike would be doing about 50kph, which in my experence with crashing bicycles at that speed it will hurt but you will live and most likely walk away from it.

I can explain it all in a really long scientificly(sp) post if you like with all the numbers and formula explaining it all

This is interesting stuff. What is your background ?

I would guess something that would require him to treat his assumptions as fact.

banga wrote:

schlek1 wrote:

disoriented wrote:

dicks-naughty-account wrote:I think all this "stopping distance" stuff is a little crap. it's all tested in perfect conditions, and the riders doing the testing have time to prepare their stop perfectly and shit. when you're thundering along you don't really anticipate a car blocking the road in such a retarded place. I doubt you could pull off the perfect stop like the figures suggest while getting the biggest, bad ass fright of your goddamn life and saying "holy cow man wtf is that doing there".

The motor bike rider was a champion racer it would be hard to belive he could stop a motorbike quickly.

I could use 0.75 seconds instead of 1 second for reaction time and it will still have the same results. In fact you will find that instead of stopping 3m short of the cop at 100kph they would stop 10m before the cop, and at 150kph they would still be doing over 100kph when they hit the cop car.

Now lets say cop the cop was lieing about the distance between them and the brow of the hill? so lets say it was 60m instead of 70m at 100kph the bike would be doing only about 25 kph when they hit the cop. If it was 50m instead of 70m at 100kph the bike would be doing about 50kph, which in my experence with crashing bicycles at that speed it will hurt but you will live and most likely walk away from it.

I can explain it all in a really long scientificly(sp) post if you like with all the numbers and formula explaining it all

This is interesting stuff. What is your background ?

I would guess something that would require him to treat his assumptions as fact.

You asked for it so i'll explain:

E= 1/2*mv2 where E=energy m=mass v=velocity 2=squared

E=mv2 means that if you double the speed you are travelling there is 4 times the energy. Now you can test this theroy at home with a bit of soft clay anobject. Drop the object onto the clay from 1m then repeat but this time dropping it from 2m you will find the indentation in the clay is 4x deeper when droped at 2m than if you dropped the object at 1 m. now if you were to double the mass of the object you drop you will find the indentation in the clay is only 2x as deep.

When you are travelling at 150kph you have 2.25 times the energy than if you were travelling at 100kph, 150/100=1.5, 1.5 squared = 2.25.

So if we use the research posted in the first post of this thread on stopping distance at 100kph (39.95, 43.17, 41.51) and average it as I don't know the exact way the rider stopped this = 41.54. More search here http://www.motorvike.com/BrakingDistance.htm which suggests the stopping distance at 60mph , about 100kph, is 134 ft or 40.84m and more stuff here: http://www.msf-usa.org/imsc/proceedings ... stance.pdf but doesn't have stopping distances from 100kph so not so good for what I want but it does from 50kph which is about 11m so if we square that it = about 44 m

So now lets assume the rider was travellling at 100kph and now we will use a reaction time of 0.75 seconds (first post research) from the time the hazard is reconized (sp) till the time the brake lever is pulled. So 100kph means your travelling at 27 meters a second. this means you will travel 20.25m before you pull the brake lever, 27 * 0.75 = 20.25m. Now we add the stopping distance to this and we get the total stopping distance, 20.15m+41.54m= 61.79m. So assuming the cop was 70 meters away from the brow of the hill the biker would of 8.21m from the cop.

Now lets assume the rider was travellling at 150kph and now we will use the same reaction time of 0.75 seconds (first post research) from the time the hazard is reconized (sp) till the time the brake lever is pulled. So 150kph means your travelling at 40.5 meters a second. this means you will travel 20.25m before you pull the brake lever, 40.5 * 0.75 = 30.38m. now as there is 2.25 times the energy travelling at 150kph than 100kph its going to take 2.25 times the distance to stop so instead of stopping in 41.54m to stop it takes the biker 93.47m to stop Now we add the stopping distance to this and we get the total stopping distance, 30.38m+93.47m= 123.84m. So assuming the cop was 70 meters away from the brow of the hill the biker would off over shot the cop car by 53.85m.

To figure out how fast the biker was going when the biker hit the cop at 150 kph, we will figure out how much of the road he would of used to slow the bike down and then the speed that he could of loss in that distanced. Of the 70m avalible to stop in 30.38m is taken up by reaction time so only 39.62 meters of road is used to stop the bike. (if you read the part proberly and a quick minded you will see that the bike is still travelling over 100kph when they hit the cop car)

We can do this by using a couple of other formula to figure out the bikes deaccelration that I can't be assed explaining but if you want to know more look them up yourself but for this we need time (t):

d=(vi+vf)/2*t therefore t= (vi+vf)/2 / d, at 100kph t=(100+0)/2 / 41.54, t= 1.2 s

acceralation = change in distance / change in time, therefore a=100/1.2, a =-83.33m per second per second

so now we have the de acceration of the bike we can figure out the speed the biker was going on impact with the formula vf2=vi2+2ad:

vf2=150*150+2*-83.33*39.62=15896 so the square root of that will give us the bikers speed on impact which = 126kph. More than 26kph over the legal limit.

And if your keen you are keen you can use the formula vf2=vi2+2ad to figure out what the effects of changing where the cop car is by change d, distance, to give you the speed of the biker on impact.

Its all basic physics and its the same stuff SCU will use and sorry for some of the shit spelling and grammer.

Well that's that sorted then.





Now where did I leave that watermelon ...........................................





Oh, and one cheer for the ref.

disoriented wrote:

banga wrote:

schlek1 wrote:

disoriented wrote:

dicks-naughty-account wrote:I think all this "stopping distance" stuff is a little crap. it's all tested in perfect conditions, and the riders doing the testing have time to prepare their stop perfectly and shit. when you're thundering along you don't really anticipate a car blocking the road in such a retarded place. I doubt you could pull off the perfect stop like the figures suggest while getting the biggest, bad ass fright of your goddamn life and saying "holy cow man wtf is that doing there".

The motor bike rider was a champion racer it would be hard to belive he could stop a motorbike quickly.

I could use 0.75 seconds instead of 1 second for reaction time and it will still have the same results. In fact you will find that instead of stopping 3m short of the cop at 100kph they would stop 10m before the cop, and at 150kph they would still be doing over 100kph when they hit the cop car.

Now lets say cop the cop was lieing about the distance between them and the brow of the hill? so lets say it was 60m instead of 70m at 100kph the bike would be doing only about 25 kph when they hit the cop. If it was 50m instead of 70m at 100kph the bike would be doing about 50kph, which in my experence with crashing bicycles at that speed it will hurt but you will live and most likely walk away from it.

I can explain it all in a really long scientificly(sp) post if you like with all the numbers and formula explaining it all

This is interesting stuff. What is your background ?

I would guess something that would require him to treat his assumptions as fact.

You asked for it so i'll explain:

E= 1/2*mv2 where E=energy m=mass v=velocity 2=squared

E=mv2 means that if you double the speed you are travelling there is 4 times the energy. Now you can test this theroy at home with a bit of soft clay anobject. Drop the object onto the clay from 1m then repeat but this time dropping it from 2m you will find the indentation in the clay is 4x deeper when droped at 2m than if you dropped the object at 1 m. now if you were to double the mass of the object you drop you will find the indentation in the clay is only 2x as deep.

When you are travelling at 150kph you have 2.25 times the energy than if you were travelling at 100kph, 150/100=1.5, 1.5 squared = 2.25.

So if we use the research posted in the first post of this thread on stopping distance at 100kph (39.95, 43.17, 41.51) and average it as I don't know the exact way the rider stopped this = 41.54. More search here http://www.motorvike.com/BrakingDistance.htm which suggests the stopping distance at 60mph , about 100kph, is 134 ft or 40.84m and more stuff here: http://www.msf-usa.org/imsc/proceedings ... stance.pdf but doesn't have stopping distances from 100kph so not so good for what I want but it does from 50kph which is about 11m so if we square that it = about 44 m

So now lets assume the rider was travellling at 100kph and now we will use a reaction time of 0.75 seconds (first post research) from the time the hazard is reconized (sp) till the time the brake lever is pulled. So 100kph means your travelling at 27 meters a second. this means you will travel 20.25m before you pull the brake lever, 27 * 0.75 = 20.25m. Now we add the stopping distance to this and we get the total stopping distance, 20.15m+41.54m= 61.79m. So assuming the cop was 70 meters away from the brow of the hill the biker would of 8.21m from the cop.

Now lets assume the rider was travellling at 150kph and now we will use the same reaction time of 0.75 seconds (first post research) from the time the hazard is reconized (sp) till the time the brake lever is pulled. So 150kph means your travelling at 40.5 meters a second. this means you will travel 20.25m before you pull the brake lever, 40.5 * 0.75 = 30.38m. now as there is 2.25 times the energy travelling at 150kph than 100kph its going to take 2.25 times the distance to stop so instead of stopping in 41.54m to stop it takes the biker 93.47m to stop Now we add the stopping distance to this and we get the total stopping distance, 30.38m+93.47m= 123.84m. So assuming the cop was 70 meters away from the brow of the hill the biker would off over shot the cop car by 53.85m.

To figure out how fast the biker was going when the biker hit the cop at 150 kph, we will figure out how much of the road he would of used to slow the bike down and then the speed that he could of loss in that distanced. Of the 70m avalible to stop in 30.38m is taken up by reaction time so only 39.62 meters of road is used to stop the bike. (if you read the part proberly and a quick minded you will see that the bike is still travelling over 100kph when they hit the cop car)

We can do this by using a couple of other formula to figure out the bikes deaccelration that I can't be assed explaining but if you want to know more look them up yourself but for this we need time (t):

d=(vi+vf)/2*t therefore t= (vi+vf)/2 / d, at 100kph t=(100+0)/2 / 41.54, t= 1.2 s

acceralation = change in distance / change in time, therefore a=100/1.2, a =-83.33m per second per second

so now we have the de acceration of the bike we can figure out the speed the biker was going on impact with the formula vf2=vi2+2ad:

vf2=150*150+2*-83.33*39.62=15896 so the square root of that will give us the bikers speed on impact which = 126kph. More than 26kph over the legal limit.

And if your keen you are keen you can use the formula vf2=vi2+2ad to figure out what the effects of changing where the cop car is by change d, distance, to give you the speed of the biker on impact.

Its all basic physics and its the same stuff SCU will use and sorry for some of the shit spelling and grammer.

I like your work! Not a big fan of maffamatix generally but in this case WOW

Yes, yes, Physics 101: Equations of Motion. Actually models the real world quite well, once you know the rate of deceleration and reaction time.

The difficulty is that reaction time and rate of deceleration vary substantially, depending on the circumstances.

In particular, the rate of deceleration varies widely depending on factors such as: the type of bike/tyres, weight of bike and rider, road conditions (surface characteristics, wet/dry), whether the bike has ABS or not, rider behaviour (force of brake application, uniformity of brake application, changing gears to use the engine as a brake), etc.

Also, the equations of motion assume motion along a level plane, so they don’t strictly apply to travelling at speed over the brow of a hill - which will increase stopping distance for two reasons:
1. Downward force on the tyres may be reduced, which delays the application of maximum braking force, and
2. Gravity will be accelerating the bike as it travels down the hill.

Consequently, calculating stopping distance is nothing like as precise as you’re suggesting - there is potentially a large margin of error, depending on the specific circumstances. That’s why onsite tests will sometimes be conducted under conditions as close as possible to those at the time of the crash. Theoretical models are fine, but they need real data to be useful.

In other words if the cop car was 70m from the brow of the hill and the motor bike was travelling at the legal speed limit the bike would of stopped 8 and a bit meters from the cop. If the bike was travelling at 150kph and the cop was 70m from the hill the biker would of impacted the cop car at 126kph. More than 26 kph over the legal limit.

So as posted earlier the only way I believe that it could be the cops fault cop was if the biker was visable to the cop before he started the u turn.

Does that win the award for most pointless use of physics in a Vorb thread, or what?

That's awesome.

I am in awe.

I wish I knew shit like that.

iodi wrote:Consequently, calculating stopping distance is nothing like as precise as you’re suggesting - there is potentially a large margin of error, depending on the specific circumstances. That’s why onsite tests will sometimes be conducted under conditions as close as possible to those at the time of the crash. Theoretical models are fine, but they need real data to be useful.

Yep I under stand that and I believe SCU do testin to figure out variables like friction between tires and road and they proberly have a larger data base of stopping distances for a give vehicle at a give fricton force between road and tire, that they can manipulate to give a more accurate result.

And if the Biker got air over the brow of the hill he was going far to fast anyway.