mivey
Senior Member
But the period is known for the average values.Except that MPH, like watts doesn't have a period.
But you do use the rate to find the quantity.Yes. But rate of heat loss isn't heat loss.
There are times when there is a definite separation between quantities and rates. One example is when you have the kWh consumed (the quantity) and would like to know the maximum kW demand (the maximum rate). Because the demand varies during the consumption period, there is no way to directly connect the two with time. The best we can calculate is the average demand (the average rate).
With a steady load, the average demand and consumption can readily be related over the consumption period. Think about a meter with an hourly demand interval. The kWh (energy consumed) and the kW demand (rate of consumption) have the same value.
With the OP's question, a steady load can be assumed for the consumption period. The average I2R (average rate) can readily be used to get the heat generated (the quantity) during the period. The period would not be an unknown in this case. So once one knows how to calculate the average power for the period of interest, the heat generated during that period can be readily obtained.
This is not the same issue we normally face with questions about power and energy conversions. Usually the poster wants to use an average value (the average demand or the energy consumed) to calculate the peak power, which we know can't be done.
The minutia about time was really making a mountain out of a molehill for the given question since time would not be an unknown and we assume a steady load for the period of interest.
The other question raised was about how a smaller wire would get hotter. It was posed as though this fact would invalidate the use of the average power to find the heat generated. The fact remains that the heat generated is different than the wire temperature. Completely different.
Many would say the power would be the primary focus for most of those items.You ought to. It's kWh you pay for.