This whole business of 'power' must be mystifying to members of the general public. They read (or hear) of h.p., W, kW, Btu/hr and so on. The incentive to really come to grips with this technical stuff must be pretty well blunted from day 1. Duncan
-----Original Message----- From: kilopascal <[EMAIL PROTECTED]> To: U.S. Metric Association <[EMAIL PROTECTED]> Date: March 6, 2002 23:35 Subject: [USMA:18593] Re: Metrication and goal setting >2002-03-06 > >I don't think most people have any concept of any of the electrical units. >The concept of current, voltage, resistance, and power and their >interrelations is foreign to most people. I'm sure most people associate >the unit watt with light bulbs. The higher the wattage, the brighter the >bulb. And with some heating elements. 1500 W is hotter than 1250 W. But >to know that the power in watts is the product of the current in amps and >the tension in volts is quite a different thing. > >If most people did have a feeling for the electrical units, they would >comprehend joules better than kilowatt hours. It would be easy to >comprehend that a 100 W bulb converts electrical energy in the form of >voltage and current into light and heat at a rate of 100 J/s. A 1500 W hair >dryer converts the same energy into heat, some light (glowing coils) and >moving air (the fan) at a rate of 1500 J/s. 15 times more than a 100 W >light. > >Unless one knows the interrelation between voltage, current, resistance, >power and energy, then the concept of energy in either watt hours or joules >is lost. > >John > > > > > >----- Original Message ----- >From: "Joseph B. Reid" <[EMAIL PROTECTED]> >To: "U.S. Metric Association" <[EMAIL PROTECTED]> >Sent: Wednesday, 2002-03-06 19:02 >Subject: [USMA:18589] Re: Metrication and goal setting > > >> Bill Hooper wrote in USMA 18506: >> >> >on 3/4/02 11:48 AM, Joseph B. Reid at [EMAIL PROTECTED] wrote: >> > >> >> Because ordinary people, as dintinct from physicists, think much more >in >> >> terms of hours and minutes rather than seconds. Electricity bills >> >> recognize this by using the hour as their time unit. >> > >> >I don't believe "ordinary" people think in terms of hours and minutes >when >> >thinking of their electric bill. I think they think in terms of >> >kilowatt-hours, but ONLY in the context that: >> >(1) their bill tells them how much energy they used IN KILOWATT-HOURS, >and >> >(2) the price they pay is given IN CENTS PER KILOWATT-HOUR. >> > >> >They have no idea (most of them) how much a kilowatt-hours is, or what it >> >has to do with "hours" at all. Many people will use the term "kilowatts" >to >> >describe their energy use in kilowatt-hours, simple dropping off the >"hours" >> >because they don't know what it signifies and don't think it makes any >> >difference. >> >> >> "Ordinary" people know what a kilowatt is. The consumptions of their >> household devices in watts or kilowatts are posted on all of them. People >> can more easily understand watts and hours than joules and seconds. The >> trouble is that our conception of time is in hours, and there is an >awkward >> 3600 seconds in an hour; and the joule is not met in everyday life. >> >> >> >> >> Joseph B.Reid >> 17 Glebe Road West >> Toronto M5P 1C8 TEL. 416-486-6071 >> >
