weird car/math question.

[specialkonrd]

ok
so lets say therse a car going 100kph, and an identical car going 200kph. Say they both have to go 400km.
Which one will use less gas getting there?
the guy going 200kph is reving alot higher but is going twice the speed.

[Sh4n3]

i've always learned that getting your car up to speed quickly uses less gas than slowly getting to your speed


that's not saying panning it though

[specialkonrd]

naw dude
if i get my car up to 60 or 70 by switching at like 4-4.5 i get worse mileage then switching at 2.5-3

im thinking the 200kph guy would get worse mileage because of wind resistance too..

[stringbeans]

there are a lot of other factors that would go into it such as engine type and gas consumption and stuff like that

john
2899131

[cyberdog]

^^^Exactly - even if the cars are identical, it would likely hinge on differences in the engine - some engines may favour faster, some slower. That said, I would guess the person going faster would use more, on average, only cuz I know a lot of the reason for the speed limits in place today was the oil crisis of the early 0s (or late 60s, don't recall at this hour)...cars going slower used less fuel, so it helped conserve it.

[specialkonrd]

well no i realize that two "identical" engines wont be the same
but for arguements sake, lets say these 2 engines are IDENTICAL in ever aspect and consume same amount of fuel

[Sh4n3]

Originally posted by specialkonrd
well no i realize that two "identical" engines wont be the same
but for arguements sake, lets say these 2 engines are IDENTICAL in ever aspect and consume same amount of fuel

i would have assuemd that was a given

common people!

[cyberdog]

What I meant was that yes, both engines would be identical, but that not all engines are identical. For example, if they were identical Honda Prelude engines versus identical Grand Voyager minivan engines, this would be a factor as these engines will have different specs and variables.

But yeah, may be my bad on the phrasing...

[mister-peenutt]

depends on how much higher he's revving.. if the guy going 100 is only at like 2000rpm.. and the other is going like 7000 the guy going 7000 will use up more gas because of the fact that you have to almost floor it to keep it up there, which means more fuel is needed which means more gas is consumed in the long run..

:Peenutt:

[Moon]

it mainly depends on how much you step on the gas (acceleration, and to accelerate you need to apply force which also requires work and that uses energy (fuel))

i find if you're going at 100, you can still run at 2000-2500rpms which isnt much at all... what takes up most up the fuel is accelerating to 100.... and accelerating to 200 would obviosuly take alot more gas, but if you can stay at 200km/h and run at 2500-3000 rpms constantly.... then hey maybe you might be able to use less gas at 200 since youLL get to your destination in half the time.

i dunno much about the numbers involved with gas consumption with cars but if someone knows (how many rpms vs gas consumption or speed vs gas consuption) then put em on this thread and us physics nerds can do the math hee hee fun fun

[Sh4n3]

Originally posted by k-pryde
it mainly depends on how much you step on the gas (acceleration, and to accelerate you need to apply force which also requires work and that uses energy (fuel))

i find if you're going at 100, you can still run at 2000-2500rpms which isnt much at all... what takes up most up the fuel is accelerating to 100.... and accelerating to 200 would obviosuly take alot more gas, but if you can stay at 200km/h and run at 2500-3000 rpms constantly.... then hey maybe you might be able to use less gas at 200 since youLL get to your destination in half the time.

i dunno much about the numbers involved with gas consumption with cars but if someone knows (how many rpms vs gas consumption or speed vs gas consuption) then put em on this thread and us physics nerds can do the math hee hee fun fun

exactlllllly


but also, like konrad said, wind resistance at 200 could change things

[SEAN!]

gear ratios would play a bigger factor inh this then anything else. alot of high performance cars have a six speed transmission because the lower five gears are more geared for performance, keeping the engine in the power bvand (where fuel consumption is much higher) the sixth gear is has a different ratio which allows for cruising at higher speeds without consuming as much fuel because the revolutiuons are kept lower.

i don't know it depends on alot of factors, but id have to say that its more likely that the car going 200km/h would burn the most fuel

[Moon]

Originally posted by Sh4n3


exactlllllly


but also, like konrad said, wind resistance at 200 could change things

wind resistance eh?

hmm interesting..... true since wind resistance is directly proportional to how fast you're moving...... but fuck the math involved with wind resistance is a lil complicated since the shape and size of the car is a big factor in determining how much wind resistance you will have.....

but hey that explains why suv's eat up so much fuel

[specialkonrd]

what are you talkin about? EVERYONE knows that a big cube with wheels is the most aerodynamic shape there is!

[Moon]

never said they werent i was talking about drag force

but then again i didnt know that they were either so i guess not everybody knows. haha whatever

[inkster]

fuck people, it's wind resistance that makes the difference here. not gear ratios. not the engines. nor any other stupid answer like that. no, it's wind resistance through and through. this is so evident, even at lower speeds, that i can't even fathom how you could all miss the obviousness of it.

here's an excerpt from Brian Beckman's "The Physics of Racing", which you should all read in totality.



"I put 55 mph and 65 mph in this table to show why some people think that the 55 mph national speed limit saves gasoline. It only requires about 7 hp to overcome drag at 55 mph, while it requires almost 12 hp to overcome drag at 65. Fuel consumption is approximately proportional to horsepower expended.

More interesting to the racer is the fact that it takes 145 hp to overcome drag at 150 mph. We know that our Corvette example car has about 240 hp, so about 95 hp must be going into overcoming rolling resistance and the slight braking forces arising from internal friction in the drive train and wheel bearings. Race cars capable of going 200 mph usually have at least 650 hp, about 350 of which goes into overcoming air resistance. It is probably possible to go 200 mph with a car in the 450-500 hp range, but such a car would have very good aerodynamics; expensive, low-friction internal parts; and low rolling resistance tires, which are designed to have the smallest possible contact patch like high performance bicycle tires, and are therefore not good for handling. "

edit: tags

[specialkonrd]

Originally posted by inkster
fuck people, it's wind resistance that makes the difference here. not gear ratios. not the engines. nor any other stupid answer like that. no, it's wind resistance through and through. this is so evident, even at lower speeds, that i can't even fathom how you could all miss the obviousness of it.

uhh dude alot of people mentioned wind resistance heh

[MC Hammered]

Originally posted by specialkonrd
ok
so lets say therse a car going 100kph, and an identical car going 200kph. Say they both have to go 400km.
Which one will use less gas getting there?
the guy going 200kph is reving alot higher but is going twice the speed.

The first one to fly off the road and off the cliff will hit the 400km mark first with the least amount of gas and therefore will make the biggest fireball. :c-tard: