mathematica physical constants without units

Question

It is helpful to use physical constants included in mathematica. Unfortunately they all include units. This provides errors when trying to integrate numerically. Is there a way just to get the value of a variable without any dimensions?

Thank you! Martin

Answer 1

If e.g. c is the speed of light:

c = UnitConvert[Quantity["SpeedOfLight"]]

Then the obvious way would be to write:

c/Quantity["Meters"/"Seconds"]

Because that way, you're certain the unitless quantity you work with actually means something in m/s, not e.g. ft/hour. In other words: If you wrote c/Quantity["Feet"/"Hours"], the result would be the speed of light, in ft/hour, without a unit attached.

Alternatively, you could always write:

QuantityMagnitude[c]

Which just returns the magnitude, without the unit

Answer 2

Perhaps this will help

In[1]:= sol = UnitConvert[Quantity["SpeedOfLight"]]

Out[1]= 299792458 m/s

In[2]:= FullForm[sol]

Out[2]//FullForm= Quantity[299792458,Times[Meters,Power[Seconds,-1]]]

In[3]:= mysol = First[sol]

Out[3]= 299792458

In[4]:= FullForm[mysol]

Out[4]//FullForm= 299792458