topic Re: Wrong Answers in Mathcad

Wrong Answers

BB_14100646 — Thu, 09 Oct 2025 00:02:22 GMT

I'm using MathCAD 9.0.0.0. I laid our 2 sets of 3 equations. One set is using variables. The other set has the values plugged straight in. The set with the variables should equal the set with the values because the values are the same, but they don't and none of them equal the correct answer.

What should happen is...

Rx=Rx=-22

Ry=Ry=211.5

R=r=213

My MathCAD program is written to follow this example...

This is how my MathCAD program looks...

Ignore the 25 degrees and the 75 degrees in the diagram. This is a homework problem altered to match the example problem so I can test to make sure it works before plugging in the values for the homework problem. Also, I'm interested in fixing the "values" problems Rx, Ry, and r. I only created those to figure out why my variable problems Rx, Ry, and R aren't working. Attached is my program.

Thanks,

Brent

Re: Wrong Answers

BB_14100646 — Thu, 09 Oct 2025 00:16:29 GMT

Something seems off with MathCAD calculation because even when I plug the "values" in the last equation...

...but when running this through Excel, I get...

212.6411

...which round up to the 213 in the hand written example.

Thanks,

Brent

Re: Wrong Answers

StuartBruff — Thu, 09 Oct 2025 00:19:04 GMT

Re: Wrong Answers

StuartBruff — Thu, 09 Oct 2025 00:24:17 GMT

Be careful of what you're squaring ...

Re: Wrong Answers

BB_14100646 — Thu, 09 Oct 2025 10:47:38 GMT

Thank you. That explains part of it, but I still need to resolve the rest.

Re: Wrong Answers

BB_14100646 — Thu, 09 Oct 2025 10:55:30 GMT

I thought I tried that yesterday, but it all seems to be working today. Thank you!

Re: Wrong Answers

StuartBruff — Thu, 09 Oct 2025 10:56:43 GMT

No worries. Is that all of your problems sorted out?

Stuart

Re: Wrong Answers

Fred_Kohlhepp — Thu, 09 Oct 2025 11:50:07 GMT

I'm sure you've already been told; "lb" is not force, it's mass. If you want force you use "lbf".

And you should know that mathcad does vector math, which can make this easy,