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Old 27th April 2014, 07:02 AM   #11 (permalink)
borat52
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Join Date: Jan 2006
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Quote:
Originally Posted by Little Nismo View Post
And don't you confuse weight and mass. Downforce effectively increases the weight of the vehicle. For any given downforce the less the mass of the car the better. But if you have a total of 1800kg from mass alone or 1300kgs mass and 500kg from downforce doesn't that, mean that 1800kgs still has to turn the corner or be accelerated? It still requires the same traction.
Yes I was sloppy with weight and mass but the above is wrong.
Downforce affects neither momentum nor kinetic energy and as such a 1300 kg car with 500kg of downforce will require 13/18ths of the braking and/or turning force of a 1800kg car.

That's the appeal of downforce, going back to our friction equation it increases R (reaction) with zero increase in mass so we can counter any given momentum or kinetic energy with more friction.

Also a weightless car in theory has zero mass so would require an infinitely small force to go infinitely quickly (ke = 1/2mv(squared) so it's not something that makes sense in the real world.

Your ute is a function of bad design, it has significant mass to accelerate but only a small mass over the drive wheels and hence the Reaction force and friction over the drive wheels is small. Iff all of its mass was over the drive wheels it would be as quick to accelerate as any vehicle with the same mass and same tyres.

The GTR is quick simply because of the efficiency in which its able to manipulate its power through the 4wd system maximising the friction on each tyre at all times coupled with a chassis and suspension set up which helps to ensure the tyres are generating lots of friction all the time.

Its weight is really a consequence of its design, not an objective in itself.

I stand by it that losing 500kg would make it significantly quicker. Yes it would spin the wheels easier but remember less mass means we need less energy to accelerate/brake so less power from the engine would give the same acceleration.
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