Is it possible to convert kg/(kWh) to litres/100m ?

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Discussion Overview

The discussion revolves around the possibility of converting units from kg/(kWh) to litres/100m. Participants explore the implications of such a conversion, particularly focusing on the roles of the units involved and the physical constants that may or may not facilitate this transformation.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • Some participants question the feasibility of converting kg/kWh to litres/100m and inquire about the implications for the units of kW and meters.
  • One participant suggests that dimensional analysis indicates kg/kWh has dimensions of time squared over length squared, while litres/meter has dimensions of length squared, implying that a direct conversion is not possible due to their incommensurable nature.
  • Another participant acknowledges the explanation of dimensional analysis but introduces exceptions where conversions might be possible, such as through the use of physical constants or specific systems like a water heater that relates energy to temperature change.

Areas of Agreement / Disagreement

Participants generally agree that a direct conversion between kg/kWh and litres/100m is not straightforward due to dimensional differences. However, there are competing views regarding the potential for exceptions based on specific contexts or physical constants.

Contextual Notes

The discussion highlights limitations related to dimensional analysis and the need for specific conditions or constants to facilitate conversions, which remain unresolved.

nb89
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kg/kWhour into litres/100m? is this possible, and if so how? what happens to the hour?
 
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I would be more curious what happens to the kW and the meters.

Do you have a specific system in mind?

Or do you want to do the conversion by using physical constants (such as c and hbar), because then I think it is not possible (kg/kWh ~ s / m^2 while l/m ~ m^2).
 
CompuChip said:
kg/kWh ~ s / m^2 while l/m ~ m^2
Close.

What CompuChip is talking about is dimensional analysis. kg/kWh has dimensions of time2/length2, while liters/meter has dimensions of length2.

You can only convert from one form to another if both forms have the same dimensions. For example, you can convert from miles per hour to meters per second because both are in the form of length/time. There is no conversion from kg/kWh to liters/meter because the two forms are incommensurable.
 
D H explained my post very well. There are however two exceptions:
1) Physical constants are not mentioned; for example energy and mass have very different units (kg m^2 / s^2 and kg, respectively) although multiplying by the speed of light squared converts one into the other
2) There is some specific system which makes a conversion possible, for example: a water heater doing so-many kW of work will heat so many water by 1 degree (actually, this case looks a lot like 1, with the "missing" quantity being the specific heat of water which can convert Joules to degrees per kilogram, for example).
 

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