>>>When I wrote about calculating every second vs. every day (for example), I was referring to the time you are modelling.
>>
>>Ah, yeah, that makes more sense. This is apart of having adjustable physical units. For example, in the speed you could use m/s or km/h or anything else one coudl dream up.
>
>For the physical units, I would suggest, to keep it simple, to do all calculations in SI units: that is, masses in kg., distances in m, velocities in m/s, accelerations in m/s^2, forces in Newton (m * kg / s^2).
>
>If you want the user to input data in any other units, like miles/hour, do this only on the input - and perhaps output - side. Convert to SI for the internal calculations.

That makes sense.