Inserting units into a range variable
2

Question

Inserting units into a range variable

CoryPad (Materials)

(OP)

4 May 05 13:21

I am using Mathcad 8.

I am trying to calculate a cylinder's mass as both diameter and length change.

I have defined the density as rho:= 7900 kg m^-3 by using Insert, Unit from the toolbar.

I have defined i:=1..8 and j:=1..9.

I have defined the diameter and length as range variables:

d[i:=0.020, 0.022, 0.025, 0.030, 0.040, 0.050, 0.075, 0.100

len[j:=0.002, 0.004, 0.007, 0.012, 0.020, 0.030, 0.050, 0.075, 0.100

I have defined mass[i,j:= π/4*d[i²*rho*len[j

The calculation provides a matrix of i rows and j columns with the correct numbers, but the units are kg/m³ because d and len do not have units assigned. I tried to insert the units in the defining equations and the mass equation, but I don't seem to know the proper syntax.

All help is appreciated.

Regards,

Cory

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rd78 (Structural) · Answer 1 · 2005-05-04 18:03:02

Cory,

A couple of possibilities ....

1.  define the units with each entry i.e. 0.02m,0.022m, etc
2.  after you have set up d and len, try multiplying by the units i.e.  d:= d*m.  Then each value of d will have the unit m.
3.  I usually set these up in a matrix and multiply the matrix by the units.

Good Luck

rd78

IRstuff (Aerospace) · Answer 2 · 2005-05-04 23:00:10

Alternately, you can also define the ancillary vectors and the assign the units with something like:

d[i:d.unitless[i*m

TTFN

CoryPad (Materials) · Answer 3 · 2005-05-05 09:18:16

Thank you rd78 & IRstuff!

Regards,

Cory

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Inserting units into a range variable
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