Young's modulus: Stress, Strain and Force for a Steel Bar

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Homework Help Overview

The discussion revolves around the application of Young's modulus in calculating stress, strain, and force for a steel bar. Participants are examining their calculations and the discrepancies between their results and those provided in a reference.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants are questioning their arithmetic and the impact of rounding errors on their results. There are discussions about the relationship between stress, area, and force, as well as the use of formulas involving Young's modulus.

Discussion Status

The conversation is ongoing, with some participants confirming values and others expressing uncertainty about their calculations. There is a focus on clarifying the methodology used to derive the results, but no consensus has been reached on the correct approach or values.

Contextual Notes

Participants mention potential rounding errors and the importance of maintaining precision in calculations. There is also a reference to a formula involving spring constant (k), indicating a possible alternative method for calculating force, though its relevance is not fully explored.

chriscarson
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Homework Statement
Problem to find strain and force
Relevant Equations
F = A E delta L
L
As all attempts to get it right but without success this is one of the problems with my workout . Where i did wrong calculations ?
The questions got the answers in brackets.
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It looks like your answers for the strain and force match the book answers. What's the problem?
 
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I know that can be rounded or something but when they have different numbers I need to be sure
 
chriscarson said:
I know that can be rounded or something but when they have different numbers I need to be sure
What’s different?
 
20200219_162629-1-1.jpg
20200219_162618-1-1.jpg


Strain and force have different numbers you can see .
 
This is just because of rounding errors. Either yourself or the author have prematurely truncated the results from previous steps.

This goes to show the benefit of working algebraically and only substituting in numerical values in the final line of working. The alternative is to use the STORE buttons on your calculator, which is much more fiddly...
 
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etotheipi said:
This is just because of rounding errors. Either yourself or the author have prematurely truncated the results from previous steps.

This goes to show the benefit of working algebraically and only substituting in numerical values in the final line of working. The alternative is to use the STORE buttons on your calculator, which is much more fiddly...
The strain maybe close but the force is way out i think.
 
When you multiplied the stress by the area to get the force, you must have made a mistake in arithmetic. When I use your calculated area, I get their force. When I divide the stress by Young's modulus to get the strain, I confirm your value of 0.00137.
 
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Chestermiller said:
When you multiplied the stress by the area to get the force, you must have made a mistake in arithmetic. When I use your calculated area, I get their force. When I divide the stress by Young's modulus to get the strain, I confirm your value of 0.00137.

So for the force you just multiplied stress with by area ?
If you have time you can work all the problem because I showed it .

we also had a formula F = k delta L , is that another way to find the F ? the only problem is what is the k .
 
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chriscarson said:
So for the force you just multiplied stress with by area ? I multiplied area, young modulus and delta L over length
If you have time you can work all the problem because I showed it .
 

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