here's a fun experiment! supposing that i need to go 1320 feet, and i do it in 4.5 seconds, what is my average velocity?

1320 / 4.5 = 293.333

293.333 is a funny number in a funny unit - its in feet per second.

so we figure there are 5280 ft in a mile and 3600 seconds in an hour, and we see that to go from FPS to MPH we divide the FPS value by (5280/3600).

If you cut a 4.5 second quarter mile, your average speed was 293.33 fps or 200 MPH, dead on.

If you cut a 4.0 quarter mile, your average speed was 225 mph.
here are the values in seconds, fps, and mph, for the spread between a 4.0 ET and a 4.5 ET, in .1s increments:

4.0 - 330 - 225
4.1 - 321.9 - 219.5
4.2 - 314 - 214
4.3 - 306.9 - 209
4.4 - 300 - 204
4.5 - 293.333 - 200

if we know the time, and that we had a standing start, what can we say about the trap speed?

Well, we cannot say anything definitively. If the change in velocity were constant (ps: the change in velocity is acceleration, and the change in a function over time is known as its "derivative", thus acceleratoin is the derivative of velocity..), then the acceleration at t(x) would be a simple line. (when f'(x) is constant, f(x) is linear)

One would expect that at the half way point, the car would have instantaneously acheived its "average" velocity. It spent the first half of the run going slower than average, and will spend the final half of the run going faster than average.

So in the constant-acceleration case with a 200 mph average speed, the start speed is 0 and the trap speed must therefore be 400mph.

The ending velocity, in fps would be 586.6 fps, and it was acheived in 4.5S, for a constant acceleration of just over 130f feet per second "squared" (per second "squared" are the units of acceleration)

Acceleration due to earth Gravity in the FPS system is about 32 fps^2, and so the 4.5s constant-acceleration standing start run is 4.074Gs for its entire duration.

Since a top fuel car does not trap at 400mph, and it also finishes the run in under 4.5s, we can say that is average acceleration is actually higher than 4G. We can also say that it's average speed is higher than 200 mph, with the majority of the acceleration front-loaded into the first half of the run.

This intuitively makes sense -- every ground vehicle has higher acceleration at lower speeds than it does at higher speeds, if for no other reason than work-required to overcome aerodynamic drag increases with the square of velocity.

The short version is this:
if you finish the quarter in under 4.5 seconds, your average velocity was higher than 200mph, and your average acceleration was higher than 4 Gs. No exceptions.

inspector01;290567 wrote:
You didn't do very good in math and phyiscs did you?? If a top fuel dragster averages 190mph, and the other car averages 200 mph over the course, the car will obviously win. Top speed, low speed, etc, don't matter at all, if the average speed is faster.

If a top fuel dragster can do the full run(reaction time and E.T.) in under 4.5 secs, then it could possibly win. But simple math says that if the car goes 200mph (again, no acceleration) the whole way, it will take 4.5 secs, so they have to beat that.

63vette;290574 wrote:
If the first car enters the "course" at 200mph and remains at that speed, its average is 200, the TDF car started at 0 at the beginning of the 1/4 pass at the exact time the first car tripped the beam then accelerated to 335mph in the 1/4 mile so its average would be substantially lower and 190 is probably close. The TFD car is capable of 4.437 so the TFD car would win if it runs a good pass.

NO NO, dont bring math into this, it is totally irrelevant and doesn't apply to real life

sarcasm,.................. I love when people argue against simple math, it is rather funny

gundar1;290841 wrote:
fact: Nitromethane messes your shit up!

truth^

good god that stuff is harsh

63vette;290574 wrote:
If the first car enters the "course" at 200mph and remains at that speed, its average is 200, the TDF car started at 0 at the beginning of the 1/4 pass at the exact time the first car tripped the beam then accelerated to 335mph in the 1/4 mile so its average would be substantially lower and 190 is probably close. The TFD car is capable of 4.437 so the TFD car would win if it runs a good pass.

And that is basically what I said, the TFD would have to run faster than 4.5 secs total to have a shot at beating the other car, especially if the other car accelerated. Reaction time has to be included too, but yes, with a perfect run, it would have a chance, even that would not be a "whooping" tho.

And the TFDs average speed would have to be higher than the cars to win, no matter what its low or top speed. So 190 mph average speed could never win.

inspector01;290567 wrote:
You didn't do very good in math and phyiscs did you?? If a top fuel dragster averages 190mph, and the other car averages 200 mph over the course, the car will obviously win. Top speed, low speed, etc, don't matter at all, if the average speed is faster.

If a top fuel dragster can do the full run(reaction time and E.T.) in under 4.5 secs, then it could possibly win. But simple math says that if the car goes 200mph (again, no acceleration) the whole way, it will take 4.5 secs, so they have to beat that.

If the first car enters the "course" at 200mph and remains at that speed, its average is 200, the TDF car started at 0 at the beginning of the 1/4 pass at the exact time the first car tripped the beam then accelerated to 335mph in the 1/4 mile so its average would be substantially lower and 190 is probably close. The TFD car is capable of 4.437 so the TFD car would win if it runs a good pass.

KA-T_240;290569 wrote:
What if the car is accelerating?

Then the time would go down, you would need to knows its average speed, or rate of acceleration, etc to figure it out. That is why 4.5 secs is the minimum. Assuming it accelerated to say, 220 mph, it would bring down the ET to less than 4.3 seconds.

inspector01;290567 wrote:
You didn't do very good in math and phyiscs did you?? If a top fuel dragster averages 190mph, and the other car averages 200 mph over the course, the car will obviously win. Top speed, low speed, etc, don't matter at all, if the average speed is faster.

If a top fuel dragster can do the full run(reaction time and E.T.) in under 4.5 secs, then it could possibly win. But simple math says that if the car goes 200mph (again, no acceleration) the whole way, it will take 4.5 secs, so they have to beat that.

What if the car is accelerating?

capitlj;290555 wrote:
The average speed of a typical top fuel run is 190+. That's the average speed including a standing start, at the big end they are doing around 315. They are gonna catch you about 1000 feet down the track and be going nearly 100mph faster.

You didn't do very good in math and phyiscs did you?? If a top fuel dragster averages 190mph, and the other car averages 200 mph over the course, the car will obviously win. Top speed, low speed, etc, don't matter at all, if the average speed is faster.

If a top fuel dragster can do the full run(reaction time and E.T.) in under 4.5 secs, then it could possibly win. But simple math says that if the car goes 200mph (again, no acceleration) the whole way, it will take 4.5 secs, so they have to beat that.

Top fuel has got nuttin on 2jz.

no chit.

capitlj;290519 wrote:
You start driving and cross the start line at 200mph then floor it. At the instant you cross the line the light goes green for the dragster. Not only is he going to whup you to the finish line 1/4 mile ahead, but he will be going so much faster than you, it will damn near blow you off the track.

This is pretty debatable, top fuel dragsters typically run mid 4's not including drivers reaction time. At a steady 200 mph (no acceleration) you will cover 1/4 mile in 4.5 secs. It would have to be a perfect pass to beat it, and even that would not be by a lot (although it would blow by you just pass the line because of terminal speed)

2wheeler;290550 wrote:
So they divided by 8?

LOL

out there;290543 wrote:
i recall reading something about funny car engines that broke down a 6k hp engine into how much power each piston was making.

So they divided by 8?

EDIT: thanks for drawing my attention to that omission.