no, the one that has the better launch would get there first cuz the other would be playing catch up for the rest.

it's the same car is what he's sayin'...

this is totally not a physics question.... this is like a middle school math word problem. you're basically saying with the exact same car... one is powered by 4 wheels the other is powered by 2 which one will reach the end first... it's obvious that the awd one will get there first. because its initial acceleration will be greater due to a great availability of traction.

what was the point of this? am i missing something profound here?

and also what was said about the the integration of the velocity vs time curve... this is misleading because if you integrated it it would give you the position at every time, if you were to compare the graphs from the two cars you'd be getting "too much info" from the awd graph because it would have hit hte 1/4 mile cut off already but you would have to keep reading the info to match up with the rwd graph. so you'd have different length graphs unless you plotted it backwards but that doesn't make that much sense because time is your independant variable.

also to find the average is to integrate it and divide by the distance however this would yield an area sum for both cars and one would be greater than the other... the areas would not be the same as you said. the greater area or rather the higher curve would indicate the higher average velocity.

i believe what you were initially trying to say was that if you had the function of posistion for both cars then you could proceed in these ways to find the respective informations. however if you have the function of position... there is very little left to calculate.

 

Definately the AWD should win. If you consider that both cars weight the same with the same drivers and both cars put the same power that means that the AWD should take the lead from the begining then maintain the lead through out the course due to the fact that still puts the same amount of power to the wehels and weights the same so Hypotetically it should take off faster and maintain same speeds as the RWD because the originator gave us equal weight and equal power.

Traction will rule on this one

 

As to your first comment, I wasn't talking about integrating to find the position vs. time graph, but rather evaluating the definite integral of the velocity vs. time graph of both cars which would in both cases evaluate to 1/4 mile.

Your second comment is absolutely correct, but your assertion that I was speaking of the areas under the distance vs. time graph is incorrect. I merely stated that the areas on the velocity vs. time graph are equal (which they obviously aren't in the distance vs. time graph) and that since they are equal and the AWD did it in less time, it must therefore have a higher average velocity.

 

if you drop them both off a 5 story building in a vacuum they will hit the ground at the same time.

 

Haha yeha I forgot that not for average velocity. Argh finals are coming up for me so im brain dead...and it' s been a while since I did vectors...

 

Very true, but I don't think that the initial question was intended to be so complicated. I think he was trying to stress that both the cars were identical, except for one being AWD and the other RWD. He even stated that there were no differences in WHP, gearing, launches, friction.

This isn't rocket science... they will finish at the same time. You are talking about the same power to the ground, same weight, same everything, and the same friction coefficient i.e. TRACTION. So right there you are saying the RWD car benefits from the same force from the asphalt back on the tires as the AWD car does. Ergo, the cars are identical, practically. The RWD car would have stickier tires to compensate for the added traction of the AWD car, cancelling the difference in the friction coefficient. What was the point in starting this thread?

 

umm... are you asking _me_ why this thread was started?
As I said a few posts back, there would be no difference [based on a number of assumptions].
The only point I was trying to add was that just because someone says he has xxxwhp, it doesn't mean that it's going to be equally quick (over a 1/4mile) as another person who has xxxwhp, even with driver ability taken into account.

 

wow this thread's still kickin and gettin very technical and complicated

 

hehe... Sorry I wasn't asking you... I was quickly trying to weed through all the other posts and yours caught my eye to respond to. I was simply agreeing with your additional point and was re-iterating what a few others, including yourself, have concluded.

 

Basically what you are looking at here is that the RWD system is going to have less rotating mass in the form of drivetrain (as well as more gearsets) so alot of power gets lost there.

However this lost power is translated to the ground more efficently at low vehicle speeds.

You really arnet going to have too much trouble hooking up a rwd car with 200hp so honestly I think the rwd car is going to win the quarter mile because of the greater efficency of the drivetrain.

The awd car is going to take it off the line but the rwd should pass it just past half track.

 

someone should compare 2 stock evo's except one coverted to rwd

 

I believe the original post talked about wheel hp. I assume that means that the inefficiencies of the drive train is accounted for(?). True that the efficiency of the drivetrain varies with speed and therefore not a constant loss, but I think if we're talking wheel hp, we can assume that the losses in the tranny has been taken care of... is this right?

 

Yes. All that matters is the torque/horsepower at the wheels which produces the force through friction with the road, to propell the car. Let me simplify the problem even more. You have two rocket(wheel) propelled cars. Each rocket(wheel) outputs the same force. One car has one rocket(rwd) the other has two rockets(awd). Which car do you think will be faster?

 

this post is silly. there is not a shred of any useful information on here. that could be from a few problems, the first being, the question is vague and leaves many other questions/assuptions. every person makes some different assumptions, and comes to different conclusions.

to the person asking the question: please define what you are looking for... and here are the topics in question:

1. tire slip/traction are you assuming that we have infinite traction? or are you assuming that we are going to get tire slip if you drop the clutch at 7krpm? if you assume we have tire slip, what kind of tire are we using? (r compound on a warm drag strip? or snow tires on ice?... etc)

2. friction/drivetrain are you assuming that both cars are identical except for the fact that one is pushing four wheels instead of 2? so both cars will have the same inertias and same drivelosses? or are you assuming that the RWD car doesn't have the added driveshafts and extra drivetrain for AWD.

3. aero these are the exact same car? if so aero can be neglected.

4. torque curve this is the torque produced at the crank (not at the wheels!!!!), however sense it is measured at the wheels, drive losses are already taken into account. if these are the same engines, we can assume they have the exact same torque curve with respect to RPM. if not, then you need to give us the torque curves for both engines to be able to get a reasonable answer

5 all others we are assuming these vehicles are identical in weight too? and we are assuming both cars are being driven by a robot that can drive both cars perfectly the same at the limit?

 

finally, maybe that will put an end to this thread, actually this thread should have died when i mentioned friction is important when comparing awd and rwd