QuantityUnit and QuantityMagnitude doesn't work

Questions
1 
Needs["StandardAtmosphere`"]
test = MeanDensity[100 Meter]
QuantityMagnitude[test]
QuantityUnit[test]

MeanDensity gives values in kg/m^3. But I can’t seem to get just the numerical value with QuantityMagnitude?

What I’m trying to do in the end is integrate the air density over all the atmosphere volume to get the total atmosphere mass. I’ll use NIntegrate afterwards.

2

Hi,

Try

test = MeanDensity[Quantity[100, "Meters"]]

Youngjoo Chung

3

QuantityMagnitude and QuantityUnit work on Quantity objects as follows

In[3]:= QuantityMagnitude[Quantity[1.21346`, "Kilograms"/"Meters"^3]]

Out[3]= 1.21346

In[8]:= QuantityUnit[Quantity[1.21346`, "Kilograms"/"Meters"^3]]

Out[8]= ("Kilograms")/("Meters")^3

MeanDensity[100 Meter] did not evaluate to a Quantity object.

In[9]:= MeanDensity[100 Meter]

Out[9]= (1.21346 Kilogram)/Meter^3

However, giving the appropriate Quantity object to MeanDensity

In[14]:= MeanDensity[Quantity[100, "Meters"]]
Out[14]= Quantity[1.21346, ("Kilograms")/("Meters")^3]

So

In[15]:= QuantityMagnitude@MeanDensity[Quantity[100, "Meters"]]
Out[15]= 1.21346
4

Thanks for the answers. Is this the easiest way of getting rid of the units of MeanDensity in preparation for integration?

Also, can the units simply be integrated somehow without problem?

5

Symbolic Integration with units:
Symbolic Calculations with Units—Wolfram Documentation