Can someone help me with this resolution Sketch ?

Forum|Forum|8 years ago
January 2, 2018
4 replies
4976 views

Can someone help me with this? I am trying to replicate this resolution on MathCad but I am doing something wrong or not using the right functions to solve it. Can someone tell me what am I doing wrong? Thank you in Advance.

ques 3,11.jpg

Other

Best answer by Werner_E

I can't open the rar-archives you attached, being told that they are corrupt.

You have a system of two equations in L and Ti. To solve this system symbolically, you would have to put the two equations in a 2 x 1 matrix and then uses "solve,L,Ti".

But Prime would choke on the units, because the symbolics are not unit aware and treats them as unknown variables. Bad, because the "unit" °C is not a simple factor but a conversion function.

Better you use a numeric solve block as shown below:

V

ValeryOchkov

24-Ruby IV

Attach please the Mathcad Prime sheet!

R

Rodyxd

Author

1-Visitor

Can you look at the file down in the next answer, please? I sent the file in the wrong reply box. Thanks

1_Questão-3-11_COPY.rar

F

Fred_Kohlhepp

23-Emerald I

Be careful with temperature units--there are two types: temperature degrees Kelvin/Centigrade and Rankine/Fahrenheit and delta temperature. Some of your values need to be deltas.

See if the attached file helps. I couldn't see a value for Ti, so I couldn't solve for L, but you can create a function.

1_shketch.zip

R

Rodyxd

Author

1-Visitor

Thanks for the Tip! The question doesn't give the Ti. It seems that can be solved simultaneously using both equations as shown in the paper.

W

Werner_E

Answer

25-Diamond I

I can't open the rar-archives you attached, being told that they are corrupt.

You have a system of two equations in L and Ti. To solve this system symbolically, you would have to put the two equations in a 2 x 1 matrix and then uses "solve,L,Ti".

But Prime would choke on the units, because the symbolics are not unit aware and treats them as unknown variables. Bad, because the "unit" °C is not a simple factor but a conversion function.

Better you use a numeric solve block as shown below:

W

Werner_E

25-Diamond I

Addendum:

Here is a way to do it with the symbolic solve command.

The trick is to get rid of the °C conversion function by providing all temperatures in Kelvin. This is achieved by using an inline evaluation after the assignment (yellow shaded areas)