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10-Marble
September 17, 2025
Solved

Wrong Answer

  • September 17, 2025
  • 1 reply
  • 619 views

I attached my MathCAD 9.0.0.0 file.

The correct answer for the 1st part is...

BB_14100646_0-1758121244062.png

If BB_14100646_1-1758121381432.png, I get the wrong answer...

BB_14100646_2-1758121452612.png

If I remove the "min" units BB_14100646_3-1758121550032.png, I get the right answer...

BB_14100646_4-1758121621139.png

...I don't know why it's doing that, but worst case, I can live with that. The 2nd part answer should be...

BB_14100646_5-1758121749984.png

However, it won't calculate the answer...

BB_14100646_6-1758121817237.png

There might be a problem with the variable Ct because before there was a box around just that variable in the equation. Now the box is around the entire equation.

 

 

 

 

Best answer by StuartBruff

Unfortunately, you've hit the perennial problem of trying to use units in an equation that has already had the units precalculated to get the desired units (eg, hour to min) and/or removed from the equations.

 

The power of 0.125 is a strong indicator that the terms inside the parentheses are unitless numbers. Indeed, the symbolic failure flags up a unit incompatibility error (note that rhs divisor adds 1/min to a number).

 

Removing units gives the following:

 

2025 09 17 B.png

 

Stuart

 

(I haven't got MP9, so didn't post the amended worksheet)

1 reply

23-Emerald V
September 17, 2025

Unfortunately, you've hit the perennial problem of trying to use units in an equation that has already had the units precalculated to get the desired units (eg, hour to min) and/or removed from the equations.

 

The power of 0.125 is a strong indicator that the terms inside the parentheses are unitless numbers. Indeed, the symbolic failure flags up a unit incompatibility error (note that rhs divisor adds 1/min to a number).

 

Removing units gives the following:

 

2025 09 17 B.png

 

Stuart

 

(I haven't got MP9, so didn't post the amended worksheet)

10-Marble
September 17, 2025

That works! Thanks!

23-Emerald V
September 17, 2025

No worries,

 

Stuart