Use DE to show error percentage

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Homework Help Overview

The discussion revolves around using differentials to analyze the impact of measurement errors on the area of a square. The original poster presents a problem involving a 2% error in the side length and its effect on the area calculation.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the use of differentials and the correct formulation of the area of a square. There are questions about the notation and variables used, particularly the distinction between the side length and the differential.

Discussion Status

Some participants have pointed out potential misunderstandings in the original poster's approach, particularly regarding the use of variables and the calculation of percentage errors. There is an ongoing exploration of the correct application of differentials in this context.

Contextual Notes

There appears to be confusion regarding the correct interpretation of percentage errors, as well as the proper formulation of the area in relation to the differential. The original poster acknowledges a mistake in their calculations.

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Homework Statement


Use Differentials to show that an error of 2% in the measurement of the side of a square results in an error of approximately 4% in the calculation of the area


Homework Equations



I'm using Area =(sΔx)^2

The Attempt at a Solution


Using Δx=0.02,
Area= s^{2}0.02^{2} =s^{2}/2500=0.04%\timess^{2}
 
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adomad123 said:

Homework Statement


Use Differentials to show that an error of 2% in the measurement of the side of a square results in an error of approximately 4% in the calculation of the area


Homework Equations



I'm using Area =(sΔx)^2
This is incorrect. The formula for area is A = s2. The differential of the area would be dA = (dA/ds) * ds ≈ dA/ds * Δs.

Don't confuse yourself by using two variables for the length of a side of the square. You shouldn't have both s and Δx in your work.
adomad123 said:

The Attempt at a Solution


Using Δx=0.02,
Area= s^{2}0.02^{2} =s^{2}/2500=0.04%\timess^{2}
 
adomad123 said:

Homework Statement


Use Differentials to show that an error of 2% in the measurement of the side of a square results in an error of approximately 4% in the calculation of the area


Homework Equations



I'm using Area =(sΔx)^2

The Attempt at a Solution


Using Δx=0.02,
Area= s^{2}0.02^{2} =s^{2}/2500=0.04%\timess^{2}

Do you really not know the difference between 4% and .04% ?
 
Ray Vickson said:
Do you really not know the difference between 4% and .04% ?

i know... i got it wrong... hence I'm asking for help.
 

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