Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: felixtheferret on 08/06/2007 23:37:09
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Hi gurus.
Hopefully this should be an easy one : I am having
trouble finding the correct word, in English, to describe
a simple equation, concerning Energy, Power, and Time:
Power = Energy or, with units: Watts = Joules
------ ------
Time Seconds
So how do you explain the term 'Power,' in English, to the layman? The answer of course, Energy divided by Time, is expressed in English typically as "the RATE of expenditure of energy." So far so good.
But what if we want to use a common English term to describe Energy in terms
of power ?
So, turn the equation around and we get :
Energy = Power * Time
So if Energy equals Power multiplied by Time, what is the elegant
way of expressing this multiplication-by-time relationship in English?
"Divided by Time" becomes "Rate" in the first example. This is because
the word 'rate' means, not 'division,' but 'division by time.'
What can I use as a substitute for "Multiplied by Time?"
please don't suggest "product" as this word is nothing to do with Time
as a quantity, unlike the word 'rate.'
I need an English word that conveys the meaning of this multiplied-by-time relationship, not just an alternative word for "multiplied by."
My only guess so far is 'time-spread.'
Basically, I want to say something like this:
Energy is the 'time-spread' of power, or with units,
"One Joule is the time-spread of power."
There must be an official English word for this, used in science.
In maths, the terms are just joined with a hyphen:
1 joule = 1 watt-second
pronounced
"one joule equals one watt second."
However this does not convey anything like the same meaning
as the word 'rate' does for 'divided by time.'
help!
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I always found the most English-Friendly expression to be "work-done".
Most people seem to have an inutitive grasp of the relationships between "work", "power" and "time".
Or put another way... Energy is the work-done by a given power acting over a given time.
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Hi Batroost,
thanks for the suggestion, I think you have identified the problem:
"work-done OVER time." There's the problem word! "Over!" Because 'over'
is ambiguous - what you mean is "during a period of time" whereas 'over' gives
me a sense of 'division' e.g. eight over 2 (over the division bar) gives 4.
So maybe 'during' is a possibility? I didn't think of that last time :
Energy = work done during a period of time ?
Energy = work done for the sum duration of a period of time ?
what do you think?
:-)
thanks...
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Energy = work done during a period of time
I like this.
Cheers,
Batroost
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"Energy = work done during a period of time"
Presumably this is to distinguish it from work that is done during no period of time?
Err, no that's silly.
Energy = work done
or, as I was taught at school
Energy is the capacity to do work
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Energy is the capacity to do work
This is true, but only if you're looking into the future. The question was more about looking into the past i.e. what has happened.
Er... yes, I konw that theoretically, then energy is capable of doing more work but I don't think that is what felix is after.
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Why the insistence on 'word equations' and cuddly explanations?
Science is just not that simple.
Energy, work, power etc. are quite sophisticated ideas and need precise definitions so that we all know what everyone means.
You wouldn't expect to describe Integral Calculus in simple everyday terms - except to discuss its aims. Nor would you restrict yourself to everyday terms for medicine or economics; it's so limiting.
The problem with over-simplification is that it can lead people to wrong conclusions and mistakes. If you 'can't get the maths' of a situation, you will probably not, actually 'get the situation' either.
Maths was a real gift for scientists and engineers - let's use it and avoid confusion.
I really am not just being elitist!