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3. Palex, how the f*** does a car accelerate at more than one g?

#### User Info: MutantJohn

MutantJohn
6 years ago#1
Apparently Formula 1 cars can accelerate at more than one g and I wanna know how.

We assume rolling without slipping as the method for acceleration therefore we claim that x double dot is equal to theta double dot multiplied by the radius of the wheel is equal to mu times g times the cosine of the angle that the road makes with the theoretical perfect horizontal. So in a perfect world x double dot can only equal g before you start to slip.

So how can a formula 1 racer accelerate upwards of 3.5 g's? This puzzles me so badly and I'm terrible at CM.
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#### User Info: MutantJohn

MutantJohn
6 years ago#2
Lol I so looked it up. Apparently, they spin the tires out to get them so hot they begin to almost melt. While they're in this ridiculously hot state the coefficient of friction is supposed to go up to match the number of g's so it can go from a c.f. of 1 to 2 to 3 to 4 to 5. How insane is that? They literally melt the rubber so that they can accelerate faster. Now that is why engineering is badass as Hell.
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#### User Info: BashyMcFetus

BashyMcFetus
6 years ago#3
The acceleration of the wheel at the point of contact with the road isn't the same as the acceleration of the car.
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#### User Info: Monsieur

Monsieur
6 years ago#4
From: MutantJohn | #002
Apparently, they spin the tires out to get them so hot they begin to almost melt.

That's drag racing, I've never seen them do it in F1, would really ruin the tires fast
What they have are some sort of electric blankets that they keep on the tires until the very last second, and the drivers get one lap to 'naturally' warm them up in the asphalt.

#### User Info: MutantJohn

MutantJohn
6 years ago#5
Nevertheless, I'm impressed. I was talking to my roommate about this and for a split second I thought all the physics I knew was wrong and I started to really freak out but thank God, I was right, I just didn't know they up'd the friction.
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#### User Info: Anarchy_Juiblex

Anarchy_Juiblex
6 years ago#6
That's drag racing, I've never seen them do it in F1, would really ruin the tires fast

This, however, they do keep their tires in a heated wrap prior to racing.
If anyone is interested.
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#### User Info: BewmHedshot

BewmHedshot
6 years ago#7
MutantJohn posted...
So how can a formula 1 racer accelerate upwards of 3.5 g's? This puzzles me so badly and I'm terrible at CM.

As far as I know they can only turn at 3.5g+, and it involves aerodynamics. Basically, the cars are shaped so that the air going around/through/over them presses down on the chassis, and the increased normal force gives the tires more traction.
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#### User Info: BigRedRacer

BigRedRacer
6 years ago#8
http://en.wikipedia.org/wiki/Formula_One_car#Performance

yeah, that says they can accelerate at only 1.45g.

also, can you (MJ) explain your math please, cuz, i'm not getting what you're trying to do. I can see that you are saying that the acceleration of the car is equal to the the acceleration of the circumference of the wheel. Then you say something about the coefficient of friction times g. but I don't get from that how you can say that the acceleration is only 1g. if mu is greater than 1, then mu times g is greater than 1g.

http://www.grandprix.com/ft/ft00308.html
http://en.wikipedia.org/wiki/Friction#Coefficient_of_friction

these sites say the coefficient of friction can get as high as 1.7, which is more than the 1.45 that the cars can accelerate at.

so that seems to be the answer.
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#### User Info: BigRedRacer

BigRedRacer
6 years ago#9
Also, like what Bewm was saying, you can't really just factor out the mass from the equation to get the acceleration since the inertial mass of the car is not necessarily equivalent to the normal force divided by g due to the downforce that is generated.

so at rest, there is no downforce, but the car is in the lowest gear which means the force due to the engine at the wheels is highest. when the car is going fast, the gear is higher and so the force due to the engine at the wheels is lower. This is why the F1 cars can corner at 3-4g but only accelerate at 1.45g. When the downforce is highest there is not enough force due to the engine at the wheel to take advantage of the higher frictional forces.

oh, and there is more drag at speed, which is a big factor in why the car accelerates slower at speed, but the gearing is a huge factor as well.
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