These units are not compatible

[RG_10050841]

Hi, 

I'm trying to input this equation into mathcad, but I keep coming into the problem of incompatible units. Thanks for the help. This is also my first time exploring physics so it may equally be my fault. The equation is in the image attached.

[StuartBruff · Accepted solution]

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@RG_10050841 wrote:

Hi, 

I'm trying to input this equation into mathcad, but I keep coming into the problem of incompatible units. Thanks for the help. This is also my first time exploring physics so it may equally be my fault. The equation is in the image attached.

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Mathcad Prime Express 7 worksheet attached.

Stuart

Edit:  The end of my 3rd paragraph should read "... and it doesn't know you can't add them".

[RG_10050841]

Thank you! I am very fresh to the software and there is a strong chance I'm an idiot. Thank you for your help in my struggles.

R

[StuartBruff]

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@RG_10050841 wrote:

Thank you! I am very fresh to the software and there is a strong chance I'm an idiot. Thank you for your help in my struggles.

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No worries.  One of the main ideas for this Community is to help people get over the initial learning barriers.  Take comfort from the fact that you are not the first person to have this problem and are very unlikely to be the last.

Sometimes even the experienced can puzzle over some error or unexpected/inconsistent outcomes!   (My bête noire is forgetting that the vectorize operator doesn't apply to the matrix transposition operator 😖)

Stuart

[Werner_E]

Additionally to what Stuart already explained in detail you may consider using the built-in gravity constant g:

Please also note that to assign a variable (like y) a value, you have to use the assignment or definition operator (":=") and not the comparison equal to (the fat "=") as you did.

[MP_10184135]

Hi my name is Mike Plunkett and I have been using MathCad for at least 20 years. I just got MathCad 7 and love it. Can you tell me how to make US my domain

unit.  For example, when I open MathCad 7 it goes to SI unit all the time, how can I get it to go to USCI  unit all the time.

Mike Plunkett

[StuartBruff]

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@MP_10184135 wrote:

Hi my name is Mike Plunkett and I have been using MathCad for at least 20 years. I just got MathCad 7 and love it. Can you tell me how to make US my domain

unit.  For example, when I open MathCad 7 it goes to SI unit all the time, how can I get it to go to USCI  unit all the time.

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Hi Mike,

Try this.  Under the Math tab in the Ribbon, select Units then choose the USCS system in the Unit System: drop down.  Seems to work.

Stuart

[MP_10184135]

Stuart: I tried just what you said went to the *Math tab,* then the
*unit System
then use the pull down menu and hit USCS*

So for the calculation, I'm working on it stays on USCS, BUT when I open
another calculation in my file it goes back to SI units??

Mike Plunkett

[StuartBruff]

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@MP_10184135 wrote:
Stuart: I tried just what you said went to the *Math tab,* then the
*unit System
then use the pull down menu and hit USCS*

So for the calculation, I'm working on it stays on USCS, BUT when I open
another calculation in my file it goes back to SI units??

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When you say another calculation in your file, do you mean the same worksheet?

I've just set a worksheet unit system to USCS.  I then entered variables using SI units and evaluated the variables.  In the both cases, Mathcad Express 7 displayed the results in USCS units.

If you mean a different worksheet, then, as Werner says, you need to create a Template with USCS as the default system.  Just choose a template, set USCS, and save it as a new template.   Choose this template when you want to use USCS.

https://support.ptc.com/help/mathcad/r7.0/en/index.html#page/PTC_Mathcad_Help%2Fto_create_a_template.html

Stuart

[Werner_E]

Guess you will have to create a template file and make it the default template in the template directory.