(Bug?) HP48 Equation Library

[Csaba Tizedes]

(02-13-2017 04:03 PM)Vtile Wrote:  Some fields of engineering are also extremely conservative, what comes how things are done and what formulas are used.

That is pretty sure! I'm a fluid flow engineer and I use by myself all the formulas in most-useful-format - as I learned many years before.

But: sometimes, for quick calculations I use some personal trick: for example the Blasius formula is f=0.3164/(Re^0.25), but 0.3164 is approximately 1/(100^0.25)=0.3162, therefore f=0.3164/(Re^0.25) = (100×Re)^(-0.25), which is easy to memorize and calculate ([EEX] [2] [×] [1/x] [SQRT] [SQRT] on my 15C).

Another hydraulic or mechanical engineer specific thing is the units: I always use Pa as pressure but for the pumps or fans I use it as J/m^3 specific energy (1_Pa=1_N/m^2=1_(N×m)/(m^3)), or for acceleration of gravity is not 9.81_m/s^2, this is 9.81_N/kg (=the force which is works on every 1 kg in the Earth gravitational field).

And of course, the area of the circle is D^2×PI/4, what else?!

Csaba