Inserting Units not giving right answer

[JW_9781974]

I am trying to achieve result with units however as soon as I input the units the answer changes 

Am I missing something 

[StuartBruff]

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@JW_9781974 wrote:

I am trying to achieve result with units however as soon as I input the units the answer changes 

Am I missing something 

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1. rpm is 1/time
2. Mathcad internally stores units as SI.  Calculations in different quantity systems that are made without all the appropriate units will likely lead to errors.

Stuart

[Fred_Kohlhepp]

Stuart is correct, but:

[ChrisKaswer]

Good points...I happened to have created a sheet many years ago for rotational topics related to this thread and attached it - in real Mathcad and Prime. In addition to torque, power and rotational speed calculations, the additional point I make in the file is relating rotational speed at a radius to "linear" speed, as built-in units pose a slight challenge here. I hope you'll find this useful as well.

Cheers,

CK

[BF_9994234]

I'm attempting to accomplish result with units anyway when I input the units the appropriate response changes

[StuartBruff · Accepted solution]

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@Fred_Kohlhepp wrote:

Stuart is correct, but:

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Quite right, Fred.  An oversight on my part, I'm afraid.

I haven't thought about it in a while, so I just did a quick recap and this is my take on what's going on.  🤔

It goes without saying that I stand to be corrected ... ☹️

Stuart