Physicist Uses Math to Beat Traffic Ticket • Hacker News Board

Re: Physicist Uses Math to Beat Traffic Ticket

#71

Post by rdl » Tue, Apr 17, 2012, 12:29 AM UTC

joshu wrote: post #68

lmm wrote: post #67

Earlier quoted context omitted.

IIRC if you use the launch control that explicitly (as in documented in the manual) puts several hundred miles' worth of wear on it - and I'd guess anyone who takes it out in a car club like that will try it at least once (I know I would). Could it just be that?

It depends on the car. On the 2010 GTR, using it at all voids the launch control. And had automatic ejection from the club, losing your membership. On the 2012 GTR, it doesn't have launch control anymore. Meanwhile some other cars have launch control which doesn't void the warranty (eg BMW 135i w/ dual clutch. Of course it has half the HP...) They sold the 2010 at around 50k miles. Similarly a f430's gearbox is only…

Do they have Tesla Roadsters?

Re: Physicist Uses Math to Beat Traffic Ticket

#72

Post by xxbondsxx » Tue, Apr 17, 2012, 2:23 PM UTC

cellularmitosis wrote: post #52

xxbondsxx wrote: post #18

Earlier quoted context omitted.

MechE here, the limiting factor for car accelerations is usually the static coefficient of friction between the car tires and the road, _not_ the power of the brakes or strength of the engine. Without ABS braking, it is quite easy to "skid" while applying a harsh brake because you overcome the limit of force between the tires and the road. Similarly, it is quite easy to "burnout" as well with a strong engine for the…

This is true for the deceleration side of things (nearly any car can lock it's brakes at any speed), but on the acceleration side of the curve, this is typically only true in first, and perhaps second gear. It would take a truly obscene amount of power to smoke the tires while already in 5th gear (assuming you dont "cheat" by popping the clutch).

Obviously burning out in 5th is almost impossible, but I was considering the stop sign case where you are starting from rest in 1st gear.

Re: Physicist Uses Math to Beat Traffic Ticket

#73

Post by xxbondsxx » Tue, Apr 17, 2012, 2:25 PM UTC

kronusaturn wrote: post #20

shasta wrote: post #19

Earlier quoted context omitted.

Car owner here. I don't think this is right.

Yeah, this argument would only apply to all-wheel-drive cars that are powerful enough to burnout on all four wheels.

It actually applies in a few cases:

* All wheel drive cars, with all-wheel braking

* Two-wheel drive cars, with braking systems that are primarily biased towards the front.

Both cases rely on either all four wheels or accel/decel or only two