[USMA:22035] Re: Fwd: [A_A] "millimeter tolerance"

[kilopascal]

Title: Re: [USMA:22031] Re: Fwd: [A_A] "millimeter tolerance"

2002-09-03   The exact same logic that allows the hectopascal to be used instead of the kilopascal, only because the familiar numbers can be used.   John   ----- Original Message ----- From: Joseph B. Reid To: U.S. Metric Association Sent: Tuesday, 2002-09-03 10:42 Subject: [USMA:22033] Re: Fwd: [A_A] "millimeter tolerance" John Kilopascal wrote in USMA 22031:   What I also noticed that was quite quaint was the use of dekanewtons:   Replacing the copper contact wire by a lighter cadmium alloy wire was considered, but dismissed on the grounds of time and cost. The critical speed of the test track catenary was then to be increased solely by increasing the tension in the wire. For the test runs, the usual tension of 2000 daN was increased to 2800 daN and exceptionally 3200 daN. For some of the faster runs over 500 km/h, the voltage in the catenary was increased from the usual 25 kV 50 Hz to 29.5 kV. Why not use kilonewton, as it reduces the number to two digits. The dekanewton is used because it is SI, instead of the obsolete kilogram-force that engineers customarily used.         1 dekanewton = 1 kilogram-force (very nearly) Hence the familiar numbers do not need to be changed when converting from the metre, kilogram-force, second system that engineers grew up with. -- Joseph B. Reid 17 Glebe Road West Toronto  M5P 1C8             Tel. 416 486-6071