I think this is a repost, but im not sure. I know I have seen this before, infact it might have been me who posted it?
And the A1GP car weighs only half a tonne...
Fun to note that the bike accelerates extremely quickly, but is outbraked by everything there. Yet another reinforcement to the donors that the laws of physics mean that no, they can't stop quicker from higher speeds than a car, despite whatever they claim.
How much quicker did you want it to be, LOL.I thought a Atom Ariel (300bhp version) was quicker??
Ah but what effect does weight have on stopping distances? Actually the weight itself doesn't play that significant a part, its far more about how that weight is distributed and how it transfers under braking.
Which leads me to the bike, could not agree more with you Famine. A common bike myth, they are far slower at stopping than cars. Mainly due to the far smaller contact patches involved and the load transfer under hard braking that shifts the majority of the load over just the front tyre. In some hard braking situations on a bike you are mainly stopping on one tyre.
True, but F=ma and ke=1/2mv^2.
The braking system of the Veyron, in order to decelerate it to rest in the same time, from the same speed (thus same rate of deceleration), as the A1GP car, must provide about 3.5 times as much decelerative effort (from F=ma) and dissipate about 3.5 times as much kinetic energy (from ke=1/2mv^2).
This actually makes the bike's effort all the more appalling, as the next worst decelerating vehicle - the Astra VXR - has about 7 times more mass, so 7 times as much kinetic energy to ditch through its discs and tyres.
The old Renaultsport Clio 172 has been clocked by AutoCar at 100-0mph at just 3.99 seconds, something only the Caterham CSR, Atom and Veyron can beat. The same braking system is fitted to the 1.6i Dynamique sitting on my driveway (though I'll assume there's some difference in tyres), which given the complete and total lack of pedal feel astonishes me yet more (and lends credence to my girlfriend's claims that her car stops quicker). Damn.
Yep - physics sai: bike suck at stopping, as any fule kno.
The Veyrons total time doesn't add up, it's total time is printed as 9.9 but it works out at only 8.9. Half a second slower than the A1GP car to 100mph and exactley the same time from 100-0, so the Veyron has done it in 8.9 seconds no 9.9.
They don't add in the reaction time, as its different for every car, and completely dependent on the driver.
They do add in the reaction time as its also an indicator of how easy it is to get on the brakes at that speed in the car.
Well, unless I can't add up (which is highly possible), they haven't added in the reaction time with the A1GP or the Suzuki.
To be used as a comparison. They may have considered an F1 car, but they're probably harder to get hold of and the cars vary so much.And why is the A1GP car in there? It's not road-legal...
To be used as a comparison. They may have considered an F1 car, but they're probably harder to get hold of and the cars vary so much.
Quite true, but as you also say this is the force that the braking system must be capable of dealing with, and brakes don't stop a car. They slow the rotation of the wheel and tyre itself, and its the limit of slip that the tyre can manage (measured as a percentage of the speed differential) that limits stopping ability.
daanHoi, this is the Auto News forum, not Physics GCSE forum.
Yep - the fact that you can lock up the wheels very easily in almost any car without ABS (or, if some silly bint pulls across 2 lanes at 40mph dead in front of you without warning, even with ABS) is a testament to the fact that the primary components of the braking system is almost always able to far exceed the capacity of the tyres to actually stop the damn thing.
Usually it's due to fade. Most breaks are great when it comes to stopping half dozen times, but as you start doing more and more (Circuit driving for example) they tend to weaken.So (sorry if it's a rather silly question), why do people upgrade the brake-systems?
So (sorry if it's a rather silly question), why do people upgrade the brake-systems?
Usually it's due to fade. Most breaks are great when it comes to stopping half dozen times, but as you start doing more and more (Circuit driving for example) they tend to weaken.
This is why Ceramic breaks are so hyped about.
So Why Would Anyone Want to Modify Their Brakes?
So, if changing braking system components does not provide "increased stopping power" or "shorter stopping distances", why even consider changes in the first place? Why not just leave the brakes alone and buy new tires? Quite simply, making changes to your braking system can have a very real, very significant impact on four other areas of brake system performance other than stopping distance:
1.Driver tuning. Modifying your brake system component sizing (brake pedal ratio, master cylinder piston diameter, caliper piston diameter, rotor diameter) can be performed to adjust the feel of the car to suit the driver’s tastes. Some drivers prefer a high, hard pedal while others prefer a longer stroke. In this regard, tuning your brakes is a lot like tuning your shocks – every driver likes something different, and there is no right answer within certain functional limits. These components can be adjusted in small steps to achieve a feel that the driver prefers.
2.Thermal control. Modifying your brake system mass (rotor weight) can be utilized if there is a thermal concern in the braking system. If your brakes work consistently under your driving conditions, then adding ‘size’ to the braking system will accomplish nothing more than increasing the weight of your vehicle. But if high temperatures are having an adverse effect on braking system performance, or other components in general (wheel bearings for example), then you should consider "super-sizing". Of course, brake cooling ducts can really help out here as well!
3.Temperature sensitivity. Modifying your brakes to address the presence of high temperatures (brake pad material and brake fluid composition) should only be considered if your thermal concerns cannot be resolved by "super-sizing". This is really just a Band-Aid for undersized systems…like those found on Showroom Stock racecars that are not permitted by their rules to upsize or cool their brakes. One might argue that it is more cost-effective to install ‘better’ brake pads and brake fluid than it would be to upsize the rotors, but all that heat still needs to go somewhere – and more often than not it will find the next weak link in the system.
4. Compliance. Any changes that you can make to your braking system to reduce compliance will increase the overall efficiency of the system – improving pedal feel, wear, and stop-to-stop consistency. Think of it as ‘balancing and blueprinting’ your braking system.
In summary, brake system modifications have their place to help make your ride more consistent, predictable, and user-friendly; however, if your ultimate goal is to decrease your stopping distance, look no further than the four palm-sized patches of rubber connecting your ride to the ground.
EE is quite right, the following is taken from the end of the (first) link on braking I posted, the 'Braking In Plain English' one, and it addresses the question you asked perfectly.
I'm feeling all light headed.Quiet right, if you want some silly times take a look at the Jag R3 and Gould hill climb cars they used in 2002.
Scaff
Thanks a lot. *Tick + One "Spread Needed"*
This also explains the comment I found (on those Autocar 2001 results) that the systems of both the M5 and the Holden GTS-R were weaker after two runs...
I'm feeling all light headed.
Indeed. Heck, I've even got my NCEA level 2 Physics exam in a few hours :|But Physics is fun!
So (sorry if it's a rather silly question), why do people upgrade the brake-systems?
Usually it's due to fade. Most breaks are great when it comes to stopping half dozen times, but as you start doing more and more (Circuit driving for example) they tend to weaken.
This is why Ceramic breaks are so hyped about.
EE is quite right, the following is taken from the end of the (first) link on braking I posted, the 'Braking In Plain English' one, and it addresses the question you asked perfectly.
Regards
Scaff
Hey any chance you could scan the 2001 results and post them up, it would be nice to add them to the collection of results we have here.
Scaff