Speed limit crackdown to cut emissions

Bloody Hell Ivan! That's just plain nasty.

 

Ah, well, if you're talking about human memory, then the three
don't belong together; by conventional wisdom, of the three possible
pairings, only two would make any sense.

--
Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD, DT175MX-MIA "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

Not entirely true; it's the length:cross-section ratio that counts
more than being tapered[1]. A bus has quite a low coefficient of drag.
Unfortunately a bus also had quite a large frontal area (Cv is drag per
area...)

[1] In a similar way that longer skis are faster (less drag).

--
Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD, DT175MX-MIA "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

Heh! With the race sprocket on, Gamma couldn't maintain legal
speeds in 6th gear in Canada -- the 110 km/h(IIRC) limit was below the
magical 6325 rpm power band, so it was only putting out at most 12 bhp and
not able to sustain speed. With the standard gearing, it had >21 bhp on
tap at the speed limit and could maintain it effortlessly. Needless to
say, I used race gearing and ignored the limit.

--
Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD, DT175MX-MIA "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

Um, no, drag goes with the square of velocity. EOS. You don't
throw in another multiplication on a whim.

As per above, double speed requires four times the power (to a
first approximation, of course).

--
Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD, DT175MX-MIA "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

Based on my experience in Bangalore I'd say it can happen.

The four hours isn't the bad part however, the bad part is 4 hours and
thirty seconds...

 

You both agree that force varies as the square of the velocity.
But power equals force multiplied by velocity so is proportional to v^3.
(Neglecting the mechanical frictional forces.)

 

^^^^
But in this case it took just 1:35:25.

 

Not sure about that, it certainly wasn't a whim! The parasitic drag
*force* increases proportionally to the airspeed squared, and hence
work done does too. But power is the *rate* of doing work, so not only
has the work done increased according to the airspeed's square, but of
course power is the rate of doing work, so as the speed has increased,
that also has to be multiplied in.

Taking a simple series of examples:

1) If drag remains constant, but speed doubles, the power required
doubles.

2) If drag increases in proportion to speed and speed doubles then
you're doing twice the work at twice the rate, ie power required is
four times as great.

3) If drag increases in proportion to the square of the speed, then if
speed doubles then you're doing four times the work at twice the
speed, ie eight times the power is required.

Looking at this month's Bike magazine's graph of top speed against
power, and looking at similar bikes, i.e. faired chain-driven
sportsbikes, we see the ZX-12R & GSXR-1000 at roughly 160BHP/180MPH

and the 1989 CBR600/FZR66 at roughly 70BHP/140MPH

The power ratio between the two sets of bikes is about 2.29.

The top speed ratio is only about 1.29.

The cube root of 2.29 is 1.32, so in fact the top speed is
proportional to *less* than the cube root of the top speed, though
these bigger bikes may suffer from being bulkier and having much
fatter tyres, which will increase both aerodynamic drag and rolling
friction.

QED.

Of course

 

Generally that holds true for me as well. Try Horse Sashimi... It had
me afraid to cough.

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Champ

I made a *fascinating* discovery the other day. I bought a couple of
packets of Fisherman's Friends and absent-mindedly ate them all in quite
a short time whilst working.

You know how a spicy curry burns when as it leaves? Well...

Very odd feeling that. I'm not sure I liked it.

--
Wicked Uncle Nigel - There are few things in life more sinister than a
public toilet with the lid closed.

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
SBS#39 OMF#6 Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (On its hols) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"
Suzuki TS250 "The Africa Single" Yamaha GTS1000