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R
ranto11-Garnet
11-Garnet
September 13, 2016
Question

Please solve the calculation

  • September 13, 2016
  • 2 replies
  • 3701 views

calc-1.JPG

Kindly solve the problem as per meow manual calc

calc-2.JPG

2 replies

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-MFra-21-Topaz II
21-Topaz II
September 13, 2016

Hi Robert,

if  P*RL = 1129 psi * in, even QL must have the same units. The algebraic csum  is made between homogeneous quantities.

Bye


For R-Anto.jpg

F
Fred_Kohlhepp23-Emerald I
23-Emerald I
September 13, 2016

psi*in = lbf/in

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-MFra-21-Topaz II
21-Topaz II
September 13, 2016

I agree completely. But the applicant has considered the mass and not the strength.

F
Fred_Kohlhepp23-Emerald I
23-Emerald I
September 13, 2016

Well, not quite

R
ranto11-GarnetAuthor
11-Garnet
September 14, 2016

Dear Sir,

Thank you for your immediate reply.

However still now i didn't get the correct answer.calc-5.JPG

F
Fred_Kohlhepp23-Emerald I
23-Emerald I
September 14, 2016

Robert;

You're getting confused by the way Mathcad handles units.

There is a difference between lb and lbf; lb is a mass unit (like slugs and kilograms.)  lbf is a force (like Newtons.)  Your equations need to be unit balanced if they're correct.  Now, you define Q as two terms, the first term has defined units:

So Q has units of lbf/in.

When you write lbs/in of circumference, you're specifying force per unit length.  To Mathcad, that's lbf/in, or N/m, or . . .

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