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JW_97819747-Bedrock
7-Bedrock
November 30, 2021
Solved

Inserting Units not giving right answer

  • November 30, 2021
  • 1 reply
  • 2004 views

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

Am I missing something 

Best answer by StuartBruff
@Fred_Kohlhepp wrote:

Stuart is correct, but:

Fred_Kohlhepp_0-1638277070885.png

 

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 ... ☹️

 

2021 11 30 j.png

 

Stuart

1 reply

S
StuartBruff23-Emerald V
23-Emerald V
November 30, 2021
@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 

  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.

 

StuartBruff_0-1638266199112.png

 

Stuart

    F
    Fred_Kohlhepp23-Emerald I
    23-Emerald I
    November 30, 2021

    Stuart is correct, but:

    Fred_Kohlhepp_0-1638277070885.png

     

      C
      ChrisKaswer16-Pearl
      16-Pearl
      November 30, 2021

      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

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