# What is the fastest letter, as it applies to cars?

By lithiumdeuterid ยท 17 replies
Jan 23, 2006
1. What is the fastest letter, in the context of cars? I don't mean which letters are used in the name of the fastest car. I'm asking what the fastest LETTER is.

Some letters I know of that have some association with speed:
c, D, E, F, I, M, R, S, T, V, W, X, Z

Thats easy!

D = Cd * r * V ^2 * A / 2

At terminal velocity, D = W. Solving for the velocity, we obtain the equation

V = sqrt ( (2 * W) / (Cd * r * A) )

The terminal velocity equation tells us that an object with a large cross-sectional area or a high drag coefficient falls slower than an object with a small area or low drag coefficient. A large flat plate falls slower than a small ball with the same weight. If we have two objects with the same area and drag coefficient, like two identically sized spheres, the lighter object falls slower. This seems to contradict the findings of Galileo that all free falling objects fall at the same rate with equal air resistance. But Galileo's principle only applies in a vacuum, where there is NO air resistance and drag is equal to zero.
So it would be 0 d v
0= airless
d= drag
v=vaccuum
zero drag= more faster! :giddy:
So, 0d is the fastest

However!
* Subsonic: Ma < 1
* Sonic: Ma = 1
* Transonic: 0.8 < Ma < 1.3
* Supersonic: 1.2 < Ma < 5
* Hypersonic: Ma > 5

3. ### toffeappleTS RookiePosts: 152

R -- R models are always the best...( i drive a vz-R so i know what im talking about!!!!!!!!)

4. ### lithiumdeuteridTS RookieTopic StarterPosts: 88

SOcRatEs:

I'm glad SOMEBODY else on this site knows something about physics. The formula for the drag force due to air (at subsonic speeds) is, as you pointed out, approximated very well by the equation:

F = (1/2) * Cd * rho * A* v^2

F is the drag force (Newtons)
Cd is the drag coefficient (dimensionless)
rho is the density of air (kg/m^3)
A is the frontal cross-sectional surface area of the object (m^2)
v is the velocity (m/s)

I would like to add something else. We can extend this approximation so we know the terminal velocity of a powered object driving horizontally. The equation for power dissipated by the drag force is:

P = F * v
P = (1/2) * Cd * rho * A* v^3

P is the power dissipated by the drag force (Watts)

This equation tells us that, gearing aside, for a given car travelling at subsonic speeds, doubling the power output of the car only gives us an increase in top speed of 2^(1/3), or about a 26% increase.

This means that if your car has 200 HP and a top speed of 150 mph, tuning the engine up to 400 HP (then adjusting gearing to compensate) will give you a top speed of about 189 mph, not 300 mph.

Oh yeah, and "c" (the speed of light) is clearly the fastest letter, but isn't used much in cars. For cars, I think I favor the F for the fastest letter.

I think I'm leaning towards "C" for various, related and un-related
reasons.
Coefficient as in wind tunnel applications, is one.

This link may have something to do with the direct Physics,
Gas Dynamics Tool Box
I think we stepped off the deep end.
The gene pool I emerge from, doesn't have a deep end! :haha:
Well, at least, I know how to "dog paddle"

6. ### AthenaTS RookiePosts: 66

To me I would say the letter Z as the Z model of many sports cars are the fastest version of those car.
Also Z rated tires are the way to go on high performance cars

7. ### hewyboTS ManiacPosts: 435

forgot one

Ya seem to have left out Q! As in: the Quintessential Quality of Quickness! Quite an omission. :angel:

8. ### lithiumdeuteridTS RookieTopic StarterPosts: 88

Hmm, perhaps. I think of small, agile cars (for example, the Lotus Exige) as being Quick, but cars with a high top speed (for example, the Ford GT) as being Fast.

9. ### hewyboTS ManiacPosts: 435

True-

I suppose the difference between "quick" and "fast" is best demonstrated in drag racing. It is not at all unusual for the losing car to have a higher speed than the winner, which begs the question: would you rather get there quicker, or be going faster when you arrive? Which, in turn, begs perhaps the most important question of all- How good are your BRAKES?? :giddy: :giddy:

10. ### lithiumdeuteridTS RookieTopic StarterPosts: 88

If your brakes are good, the next question is, how good are your tires? Tires are very important. Tires make or break the race. Tires are very important. There are all kinds of secret recipes for making tires with the highest possible frictional coefficient while keeping the lowest amount of 'shedding' of rubber. Tires are very important.

Tires are also very important.

P.S.
Tires are important.

11. ### hewyboTS ManiacPosts: 435

Ok

Alright, let's recap:
Quick and fast are not necessarily either, so neither will make or brake the argument.

Perhaps we should retire this discussion, and start a new tread? :wave:

12. ### SNGX1275TS Forces SpecialPosts: 10,742   +422

If your tires are that good (in relation to the ground) for breaking, then you need to worry about how good your vechile is, or how well you are strapped in Then, are you, yourself even able to handle that without being killed.

13. ### SpikeTS EvangelistPosts: 2,168

And none of it really matters if the damned engine won't start

In my observations, SciPhysics and SciFi are the engine of imaginations.
One will discount the possible, one will dream the impossible, "Both"
step out of known reality to invent the future.
As applied to this thread and the subject of Alpha letter in contrast to fast/est
cars.
Here @ TS, it appears, "both engines" are running smoothly!
Stepping into, "the not so distant future",
Will the alphabet and cars even matter?
Will they finally lets loose the "the Ginie the in bottle" Hydrogen?
Or will we actually get the "Star treky" transporter? (Which makes
me wonder why did they need a ship?)
Einstien= cars moving close to speed of light, when headlights turn on,
will you see or pass the light beams.

15. ### hewyboTS ManiacPosts: 435

simple

SOc- once you pass light-speed, ya just drive usin the rear-view mirror- that's where all the light is! :angel:

16. ### SpikeTS EvangelistPosts: 2,168

According to Einsteins theories, the closer you get to light speed, the smaller you get

17. ### hewyboTS ManiacPosts: 435

No prob

That'd be Ok- the booster seat you'd need would give you a better view out that rear-view mirror. You could have your wife work the pedals, keeping her busy so she couldn't back-seat drive!! (uh-oh- now NOW is gonna get after me) :rolleyes:

Very punny.