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## Re: I want to find torque from standard power formula without changing equation to t=p*30/(pi.n)

Attached is a sheet for you in Prime 3 format to give it a try.

If your trial isn't over, this is what you should see (if you trial period is over you will see the very same, too, but it will go away if you try to change values and/or recalculate the sheet):

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## Re: I want to find torque from standard power formula without changing equation to t=p*30/(pi.n)

 suyog patil wrote: It is not working in Express Prime 3.1

With Express the only way to solve your problem is

## Re: I want to find torque from standard power formula without changing equation to t=p*30/(pi.n)

I guess I don't understand the question and the use of solve blocks in some of the other replies.

Here's my Mathcad 15 statement of the problem.  Or course you can change the output units to whatever you like

Here's the Mathcad Prime 3.1 view in with mks units.

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## Re: I want to find torque from standard power formula without changing equation to t=p*30/(pi.n)

I agree on and already had stated above that symbolics solve and the usage of a solve block are overkill in this case.

But the question was "how to find T   Without making equation relating torque like   T=p*60/(2piN)".

So manually solving this more than easy equation was obviously not the way to go. I assumed (and I am not that sure in the meantime) that the OP just used this equation as a simple example and had a much more complicated equation in mind, where manual solving would require much more effort or would not be possible at all. Thats the reason for the symbolics and solve block you see all over this thread.

Another reply of the OP which I did not fully understand led me to believe, that he wanted do the calculation with different input values. Therefore I suggested the creation of functions.

Werner

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## Re: I want to find torque from standard power formula without changing equation to t=p*30/(pi.n)

Werner and Craig you both are correct to solve the simple way. Why cant we find any variable from standard formula without manipulating equation, as most of the errors are found in manipulating formulas. Consider following example.

Standard Formula is P=w*T

1- find T using inputs w and p (20rpm, 10kw)

2- find w using inputs p and T (25kw,10kNm)

3 - find P using inputs w and T (1000 rpm , 16kNm)

Now with same standard formula we have manipulate the equation 3 three times. Is this not time consuming.

Now this very simple formula, what for complex formulas. Is it not time consuming.

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## Re: I want to find torque from standard power formula without changing equation to t=p*30/(pi.n)

> Why cant we find any variable from standard formula without manipulating equation,

You can! And it was shown in this thread how. But of course you have to tell Mathcad every time which equation to solve for which variable.

You can use:

1) symbolic solve

2) numeric solve block

3) root function

The first two are not available in the limited but free Express version of Prime.

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Straight up!

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## Re: I want to find torque from standard power formula without changing equation to t=p*30/(pi.n)

Now can tell how to find the unknown variable Drr..it get complicated to go simplify...

or

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## Re: I want to find torque from standard power formula without changing equation to t=p*30/(pi.n)

Your first example just returns the guess value because there is no constraint, just a function definition.

Your second example looks like it should work. We don't see what the error message is and can't play around with it as you didn't attach your sheet.

It looks like your formula for f is wrong, as your first summand is of dimension length^3 but the second is length^-3 !!

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## Re: I want to find torque from standard power formula without changing equation to t=p*30/(pi.n)

Maybe it should be that way:

Werner

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