Message text written by "Ptegler"
>We're in a terminology conflict here! He He
If it takes 'work' to start the process.... work
must be preformed to maintain it.
physics is physics.... unless the car is moving
at the speed of light then we can bend the rules a bit.
But for us 'earthlings'... and engine running...is producing
AND using... energy. The amounts and where they go
have nothing to do with it.
An engines 'efficiency' is relative to the task.
task / work = rate The rate can change. Hence
a simpler term... 'efficiency' is used (usually incorrectly)
<
The terminology conflict here isn't about physics but about what
constitutes the physical plant. I'm saying that the engine along with the
cooling system, the alternator producing enough current to cover the energy
used for the ignition system, cooling fans, fuel pump, etc as need be
constitute the power plant. Power lost to the pumping losses in the
cooling system, the lubrication system, fuel system are not considered part
of the output of the power plant but are overhead.
Consider this analogy: Suppose you have a business that produces a
product. It costs $15 in parts and labor to produce this product and you
sell it for $18. That's a $3 profit. But lets say that the rent and
utilities, accountant fees, bank loan payments amount to $3 for each unit
sold. Well your $3 profit is now zero. You have no profit. This is the
difference between gross and net.
Efficiency is the same way. An idling engine is consuming fuel. It is
generating torque in the crankshaft. But all that torque is going to
turning the oil pump, the water pump, the alternator, the input shaft on
the transmission, etc, and the net output is zero. Efficiency is defined
as energy out divided by energy in. Zero divided by any number (other than
zero) is zero.
If the engine were shut down then energy in would also be zero and
efficiency would be undefined (zero divided by zero is undefined).
Enough physics. I gotta go back to work.
Dave
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