Your theory is sound but totally impractical in reality. That's why acceleration is not worked out the way you mention it. I don't want to turn this into a discussion about car performance - I would suggest going to pistonheads for that. Suffice to say that being a car enthusiast for many many years I have never seen acceleration figures being calculated without someone sitting behind the wheel and pressing the right pedal down as far as it will go ;-)
From: [EMAIL PROTECTED]: [EMAIL PROTECTED]; [EMAIL PROTECTED]: RE: [USMA:40016] RE: BBC News presents news about a new vehicle in metric onlyDate: Tue, 8 Jan 2008 20:13:16 +0000 Steve, I did not suggest that one could directly calculate acceleration from the figures provided, I stated that one could calculate the “maximum theoretical acceleration”. For example, the Mercedes Benz CLK (the gas guzzler featured in this weeks Sunday Times) has a stated time of 4.3 s to reach 60 mph. The theoretical minimum time is 1.95 s (assuming maximum power for the entire acceleration period and also that there was no drag). The formula (making these assumptions is) t = mv²/2P where m is the mass of the car, v its velocity P its power. I used kg for mass, m/s for velocity and W for power (giving a consistent unit set). If you try doing the same using imperial units, you must either convert HP to some ridiculous unit such as pounds feet² per second³ or introduce an equally ridiculous constant to take into account the non-consistency of the imperial system. You can verify the above formula for yourself by assuming that the energy produced by the car is P·t and that this energy has all been converted into kinetic energy and equating the two energies and solving for t. Of course, I did not include drag which is one of the reasons why the maximum theoretical acceleration is greater than the true acceleration. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Stephen HumphreysSent: 08 January 2008 10:12To: U.S. Metric AssociationSubject: [USMA:40016] RE: BBC News presents news about a new vehicle in metric only Acceleration cannot be calculated from that as you need to factor in the power curve of the vehicle (eg, turbo, diesel, high compression etc).It's the reason why many British cars have phenomenal acceleration from a small (eg 1.8 L) car compared to an American counterpart with a huge engine (even when you factor in the weight [dis]advantage). Also - as I have mentioned, acceleration becomes quite variable with high performance cars (sub 5 second types). From: [EMAIL PROTECTED]: [EMAIL PROTECTED]; [EMAIL PROTECTED]: RE: [USMA:40009] RE: BBC News presents news about a new vehicle in metric onlyDate: Mon, 7 Jan 2008 22:23:00 +0000 Steve, If you visit http://eur-lex.europa.eu/LexUriServ/site/en/oj/2002/l_018/l_01820020121en00010115.pdf you can see the list of items that need to be specified of a type-conformance test. Although acceleration is not included in the list, the maximum power, maximum speed and weight of the vehicle are included. It is therefore possible to calculate the maximum theoretical acceleration of a car. Tests done by the car magazines serve only to cross-check the parameters measured by the authorized laboratories that made the official measurements. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Stephen HumphreysSent: 07 January 2008 11:32To: U.S. Metric AssociationSubject: [USMA:40009] RE: BBC News presents news about a new vehicle in metric only A zero to 60 and zero to 62 figure can vary somewhat as the state (in any shape EU *or* democratic) cannot force private enterprise to accept their figures if indeed they carry out perfomance related tests. For instance a Lotus Esprit can be quoted as 0-60 and 0-62 for various times between 4.3 and 5.3 seconds depending on magazine, TV show, guides, etc Also - Germany has a top speed limit of (as reported in the UK) 155mph whereas no such limit exists in the UK. So yes, we still have a few freedoms left to think for ourselves (this does not distract me from wanting us to leave the EU though).> From: [EMAIL PROTECTED]> To: [email protected]> Subject: [USMA:39991] RE: BBC News presents news about a new vehicle in metric only> Date: Sat, 5 Jan 2008 07:59:35 +0000> > Of course, there is no such thing as an "EU law", is there? I was under the impression that the member states agree to implement identical laws and then each member state's legislature must approve and implement the law.> > Does anyone have any idea how this is carried out in the UK?> > Ezra> > -------------- Original message ----------------------> From: "Martin Vlietstra" <[EMAIL PROTECTED]>> > Under EU law, all new car models must undergo standard tests which include> > acceleration, top speed, fuel consumption etc. It is surprising how many> > UK car magazines quote the time taken to reach 62 mph (without further> > explanation).> > > > -----Original Message-----> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf> > Of [EMAIL PROTECTED]> > Sent: 05 January 2008 04:46> > To: U.S. Metric Association> > Subject: [USMA:39989] BBC News presents news about a new vehicle in metric> > only> > > > I came across the news video report below on the BBC News web site> > (International Edition) that describes a French car that uses compressed air> > to drive the engine:> > > > http://www.bbc.co.uk/mediaselector/check/player/nol/newsid_7170000/newsid_71> > 71000?redirect=7171043.stm&news=1&nbwm=1&nbram=1&bbwm=1&bbram=1&asb=1> > > > I presume that the fact that this is on the Int'l Edition explains why all> > the info about the vehicle is in metric, including the top speed (since all> > speed limits in the UK are still in Imperial only).> > > > Still, it was fun to see the metric (and to learn about the car!)> > > > Ezra> > > Messenger on the move. Text MSN to 63463 now! Think you know your TV, music and film? Try Search Charades! _________________________________________________________________ Who's friends with who and co-starred in what? http://www.searchgamesbox.com/celebrityseparation.shtml
