Anyone good at formulas in Excel 2007?

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Discussion Overview

The discussion revolves around creating and troubleshooting Excel formulas for specific calculations related to mechanical systems, particularly involving rod length and throttle body throat area. Participants seek assistance in translating mathematical formulas into Excel syntax while ensuring accuracy in calculations.

Discussion Character

  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant presents a formula involving rod length, half stroke, and crank angle, seeking help to implement it in Excel.
  • Another participant provides a specific Excel formula that incorporates the necessary calculations and cell references for the first query.
  • A subsequent participant introduces a new formula related to throttle body throat area, questioning the correctness of their Excel implementation and whether to use radians.
  • There is a request for clarification on the need for the "RADIANS" function in the context of the second formula.

Areas of Agreement / Disagreement

Participants generally agree on the need for assistance with Excel formulas, but there is uncertainty regarding the correct application of radians in the second formula, indicating a lack of consensus on that point.

Contextual Notes

Participants have not resolved whether the use of "RADIANS" is necessary in the second formula, and there may be assumptions about the accuracy of the mathematical expressions used in Excel.

5.0stang
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Okay, the formula that I am working from is:

(RL+S) – sqrt [ RL^2 – (S*sin CA)^2 ] – S*cos CA

Rod Length = RL = 5.090
Half Stroke = S = 1.5
Crank Angle = CA = 107.5

With numbers plugged in (my version?):

(5.090+1.5) - sqrt [5.090^2 - (1.5*sin (107.5))^2] - 1.5*cos (107.5)

The final answer should be 2.156.

How can I put this into an Excel spreadsheet so I can just change out the 3 inputs and get the correct answers for each?

Thanks for any help!
 
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Put your values into these cells:

Rod Length -- A2
Half Stroke -- B2
Crank Angle -- C2

And paste this equation into E2:

=(A2+B2)-SQRT((A2^2)-(B2*SIN(RADIANS(C2)))^2)-B2*COS(RADIANS(C2))

Hope that helps!
 
It sure does, thanks!
 
Nevermind.
 
Last edited:
Okay I got another one that I need help with. Maybe someone can help explain it to me. :)

Formula on paper looks like:

(Pi*d^2/4) * 1-((cos(Open Angle + Closed Angle)) / (cos(Closed Angle)))

I am using this for a throttle body throat area formula.

D = Minimum Diameter and I am using 2 for now.
Open Angle = 75
Closed Angle = 15

They both equal 90 degrees.

I put it in Excel like this:

=((3.14*(B1)^2)/4)*(1-(COS(D1+C1))/(COS(C1)))

The answer was 1.29.

Did I do any of this correctly? Do I need to insert "RADIANS" anywhere?
 

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