Where the watt is used by American industry, beware of the so-called air watt. It is a stupid ifp unit, very close to the real watt. This folly is used in vacuum technology and also for the rating of vacuum cleaners. How ridiculously far they go to avoid using SI, even inventing monstrosities like that! The air watt can be found in Rowlett''s Dictionary under A, http://www.unc.edu/~rowlett/units/index.html
Han ----- Original Message ----- From: "Ma Be" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Tuesday, 2002-03-05 01:34 Subject: [USMA:18535] Watts and treadmills On Sat, 02 Mar 2002 22:05:44 Barbara and/or Bill Hooper wrote: ... Similarly, 55 kW means you use 55 kJ each second, so if you use energy at that rate for 15 minutes (which is 900 s), you find you have used 55 000 kJ (or 55 MJ) of energy. That value can be related to the heat energy produced (measured in joules) or mechanical energy produced (in joules) or.. I'm glad Bill brought this up. I'd like someone here to help me understand the relationship between the figure that treadmills/bicycle exercising machines give us in W with energy we used (which, unfortunately, is invariably reported in calories). Something simply is not making any sense to me. Yesterday I was monitoring how my wife was doing in the bike machine and I'd say she was spending an average of 120 W+ in her exercise routine. Upon checking the calorie reading it was stating that she spent about 260 calories during her 30-min session! Am I missing something here?... Note: Doing the calcs would give us the following: 120 W x 30 min x 60 s = 216 kJ =~ 52 Cal This is intriguing because I know I usually spend about 2 MJ of energy per half-hour of running I do on my treadmill at ~12.5 km/h speed.
