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tfoley-21-Visitor
1-Visitor
June 15, 2016
Question

Units for CTE

  • June 15, 2016
  • 2 replies
  • 5461 views

I am new to MC 3.1 and struggling with units.  For instance, how do you input the units for the coefficient of thermal expansion - 1/F or 1/K?

2 replies

L
LucMeekes23-Emerald IV
23-Emerald IV
June 16, 2016

Just enter the unit (K or F) then raise it to power -1, by typing

^-1

to get:

Or

After the numeric value type

*1/

then add the unit, to get:

Success!
Luc

V
24-Ruby IV
ValeryOchkov24-Ruby IV
24-Ruby IV
June 16, 2016

R
RichardJ19-Tanzanite
19-Tanzanite
June 16, 2016

IMO, overwriting the built in units so that °F is wrong is not a good solution, and may lead to serious errors elsewhere in the worksheet.

R
RichardJ19-Tanzanite
19-Tanzanite
June 16, 2016

Temperature units are confusing, because you cannot simply convert one to another using a scaling factor. When using units other then Kelvin or Rankine you must distinguish between a temperature, and a change in temperature. For example:

T=300°C

ΔT=20°C

The obvious conclusion is that the new temperature is 320°C. But suppose I convert to Kelvin, and then add:

T=573.15K

ΔT=293.15K

So the new temperature is 866.3K=593.15°C. This answer is wrong because the change in temperature was treated as a temperature relative to absolute zero, and not a change in temperature. This is why Mathcad provides the units °C, Δ°C, °F, and Δ°F.

With that in mind,

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