Tor Olav Kristensen wrote:

> 1 mile
> = 8 furlongs
> = 80 chains
> = 1760 yards
> = 8000 links
> = 5280 feet
> = 15840 hands
> = 63360 inches
> 
> 1 furlong
> = 10 chains
> = 220 yards
> = 660 feet
> = 1000 links
> = 7920 inches
> 
> 1 chain
> = 22 yards
> = 66 feet
> = 100 links
> = 198 hands
> = 792 inches
> 
> 1 yard
> = 3 feet
> = 9 hands
> = 36 inches
> 
> 1 foot
> = 3 hands
> = 12 inches
> 
> 1 hand
> = 4 inches
> 
> 1 inch
> = 1000 mils

THANK GOD FOR METRIC!!! >_<

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Tor Olav Kristensen wrote:
> 
> 1 mile
> = 8 furlongs
> = 80 chains
> = 1760 yards
> = 8000 links
> = 5280 feet
> = 15840 hands
> = 63360 inches
> 
-clip-
> 
> 1 inch
> = 1000 mils
> 

I think I'll stay preferring the metric system.

-- 
Eero "Aero" Ahonen
    http://www.zbxt.net
       aer### [at] removethiszbxtnetinvalid

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Orchid XP v8 wrote:
> THANK GOD FOR METRIC!!! >_<
> 

What he said.

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On Sun, 18 May 2008 18:44:19 +0200, Tor Olav Kristensen
<tor### [at] TOBEREMOVEDgmailcom> wrote:

>
>1 mile
>= 8 furlongs
>= 80 chains
>= 1760 yards

Where were you when I was at school :-)

Your post looks like the back of my old school jotters :-)

Yes we had to learn all that stuff by heart.
-- 

Regards
     Stephen

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> The engine is directly coupled to the wheels.

Assuming the clutch is engaged, yes this is pretty much true, the only tiny 
difference can come from twisting in the driveshafts and bending of the 
teeth on the gears.  So it's pretty much coupled :-)

> Unless the car looses traction, the forward motion of the car and the 
> rotational speed of the wheels and engine all have a simple linear 
> relationship.

Except pretty much the whole time, part of the tyre has lost traction with 
the road, if it hadn't then it would mean there were no forces being 
generated, and you wouldn't go anywhere.

There's a quantity called "slip ratio", which is the ratio between the 
actual speed the wheel is rotating, and what it "should" be (ie vehicle 
speed divided tyre rolling circumference).  The slip ratio (SR) is never 
exactly 1, only when you are applying no forces to the wheel (ie no power 
and no braking).  If you brake moderately hard, it can easily go down to 
0.8, and under normal acceleration can be 1.05 or so depending on your 
tyres.

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>> There is, in a (relatively primitive) manual transmission. There is not,
>> however, a linear relationship between engine RPM and gasoline usage.
>
> How many cars use a transmission that would count as "relatively
> primitive"?  But I do agree that there's not a linear relationship
> between RPM and MPG.

I'd say that about 90% or more of cars sold here in Europe the transmission 
is a "relative primitive" manual.  The reason is for efficiency, any extra 
junk in the transmission (like fancy fluid couplings or multiple-clutches 
etc) just increases fuel consumption.  You connect the engine as directly to 
the wheels as you possibly can, otherwise you're just wasting energy.

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> If I put my car into top gear and set the engine to 3,500 revolutions per 
> minute, my car travels forward at almost exactly 75 miles per hour. So... 
> how far forward does it travel for a single revolution of the engine??

I'll assume the other answers are correct, 0.57 meters.

> Similarly, at that speed my car achieves roughly 50 miles per gallon of 
> fuel. So how much fuel does it inject into each cylinder??

50 miles per gallon = 5.6e-5 litres per meter according to google.

Which is about 3.22e-5 litres per revolution.

Let's use units of mass here, because I think it's easier to imagine the 
amount, so we have about 24 mg of petrol being used per revolution.

So in your engine, that means 12 mg of fuel is being injected each time into 
each cylinder (the fuel is injected every 2nd revolution into each 
cylinder).

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> I find the fact that such a seemingly miniscule amount of fuel can be used 
> to propel quite massive vehicles along at such speeds quite amazing.

And they are improving all the time - I'm pretty sure that in my new car 
I'll be able to do 1000 km on a single 50 litre tank if I take it easy (just 
got 780 km on my first tank, but a lot of that was going over 160 km/hr!). 
Even 5 years ago that would have been impossible in most cars.

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Paul Fuller <pgf### [at] optusnetcomau> wrote:
> I find the fact that such a seemingly miniscule amount of fuel can be 
> used to propel quite massive vehicles along at such speeds quite 
> amazing.

  Once the car is moving it only requires the amount of fuel necessary
to overcome the friction which would otherwise stop the car. Given that
the car has an enormous amount of momentum, the amount of energy needed
to keep it against such small things as air friction isn't all that large.

  Compare it to the amount of fuel needed to get the car from 0 to 100 km/h
in a relatively short amount of time.

-- 
                                                          - Warp

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> to keep it against such small things as air friction isn't all that large.

At 75 mph air friction isn't small.  A lot of small cars give up not much 
faster than this because their engine cannot generate enough power to 
overcome the air friction.

>  Compare it to the amount of fuel needed to get the car from 0 to 100 km/h
> in a relatively short amount of time.

Much less than getting to 100 km/h in a long time...

IMO, the surprise at the small amount of fuel needed comes from the fact 
that the energy density of petrol is so high.  We hear figues like 6 litres 
per 100 km, but 6 litres of petrol equals around 200 MJ of energy, enough to 
lift a 747 plane 100 metres in the air!

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