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2002-11-17
They should use kilojoules. Kilojoules is SI,
Calories are not. Calories is actually a confusing term. The "large
calorie" spelled with a capital C in the use is really a kilocalorie.
So, if you are eating 1500 Calories a day, you are really eating 1 500 000
calories. Most people do not know this. This may have come about in
order to eliminate the use of the prefix kilo. So, I'm sure most Americans
assume the calorie is not a metric unit. The calorie is an old metric
unit, not part of modern SI. The term calories can continue to be used in
marketing as a synonym for energy. Thus when something has less calories,
it means it has less energy.
Kilojoules are better for dietary concerns as there
is an exact relationship between energy expended in joules and the energy
needed to power a machine (such as an exercise bike) whose mechanical work is
described in newton metres (= joules). If the machine is connected to
an electric generator and that generator supplies and electrical load, a
wattmeter can be attached to describe the power being produced in
watts. For every second that power is produced, that is the amount of
energy converted from mechanical to electrical to thermal (or whatever the load
may be) form. Since there are losses in the conversion (in the form
of heat and windage) , the actual power produced by the person is maybe 10 to 20
% more.
There is really no reason to continue to use
calories.
John
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- [USMA:23417] Nutrition Matthew Zotter
- kilopascal
