Proektsoftbg
[Enhancement] Rpm to rad/s conversion
Hi,
it seems that Calcpad can't convert rpm to rad/s. Could you add such a possibility? Maybe also rpm and rad/s to Hz.
Btw. The rpm unit is really confusing and often discussed on online forums of engineering math software. Is 1 rpm=(2*PI)/60 rad/s in Calcpad?
Hi! Good question!
Historically, rpm came before angle units (rad, deg, grad, rev) in Calcpad. So, it is not defined upon radians. Angles are in a separate dimension layer. rpm are defined as "time^-1" and not "angle/time". That is why rpm can convert to Hz and 1/s and not to rad/s.
Also, rad/s cannot convert to Hz for the same reason. This is a limitation that comes from the internal representation of units in Calcpad. There is a reason to keep the angles in a dimension layer. If we remove it these conversions will be possible, but angle units will be lost after each operation.
Now, if you write in Calcpad: α = 30° + 15°, you will get α = 45°. And you can continue using this value in further calculations. Otherwise, you will get it like in MathCAD:
MathCAD can convert rpm and Hz to rad/s but cannot keep angle units attached to variables.
In Calcpad, you can use a workaround:
- To multiply your variable to rev and then convert to rad/s:
f_1 = 10rpm
#hide
f_1 = f_1*rev|rad/s
#show
f_1
- To define your custom Rev units that depends on rev/min:
.Rpm = rev/min
10Rpm|rad/s
Thank you very much for this detailed explanation and workaround suggestion. I've never used MathCAD but I know that SMath internally converts all inputs to SI units (rad, m, kg and so on) for calculations and then only converts the results to the specified unit if needed.
SMath works just like MathCAD. IMHO, if everything in my equation is in mm or deg, it would be preferable to obtain the result also in mm and deg, in most cases. It is tedious to convert it back every time.
However, both MathCAD and SMath work differently from Calcpad. They have graphical input interface with special placeholders for units. Calcpad uses the codding approach and you have to use vertical bar | conversion instead.
But the main difference is that Calcpad has the unique feature for variable substitution in equation. That is why it needs to retain the original units in order to substitute them properly. And that made us to introduce the special dimensional layer for angles with is not consistent with dimensionless units.
Probably, it is possible to override the dimensional consistency for the special cases of rpm and Hz and force them to convert to rev/min or rad/s by exception. I can think of that...
Probably, it is possible to override the dimensional consistency for the special cases of rpm and Hz and force them to convert to rev/min or rad/s by exception. I can think of that...
That would be great, those units are quite commonly used and easy conversion between them could be really helpful.