Calculating amount of compression a bone can withstand

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Homework Help Overview

The discussion revolves around calculating the amount of compression a bone, specifically a femur, can withstand before breaking. The problem involves concepts from material science, particularly related to stress, strain, and Young's modulus.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of the stress = elastic modulus x strain equation and question how to relate the given values to the problem. There is exploration of the relationship between stress, force, and area, as well as the implications of strain on length changes.

Discussion Status

Some participants are clarifying the definitions of elastic modulus and stress, while others are attempting to connect these concepts to the problem. Guidance has been offered regarding the understanding of stress and its calculation, indicating a productive direction in the discussion.

Contextual Notes

Participants express uncertainty about certain parameters, such as the area needed for calculations, and the implications of the given values on the overall approach to the problem.

sruthis
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Please I need help with this question. I know I have to use the stress = elastic modulus x strain equation, but i do not know how to apply it to this particular problem.


A Bone has a young's modulus of about 18 x 10^9 Pa. Under compression, it can withstand a stress of about 160 x 10^6 Pa before breaking. Assume that a femur (thighbone) is 0.50 m long, and calculate the amount of compression this bone can withstand before breaking.
 
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Hi sruthis, welcome to PF. In this problem, what is the elastic modulus? What is the stress? How is strain related to change in length? You have the right equation, now you just need to apply it correctly. Try to carry the units along with the numbers to avoid making an error.
 
I think I need to somehow use the equation F/A = Y(change in L/Linitial) and solve for Linitial, and i guess plug that value into the stress equation? but i do not know how to find A, and I am not sure if I have the right idea.
 
You're already given the stress, you don't need to find it by dividing force by area.
 
ohh. thank you so much. i completely did not realize that F/A was the stress. Thank you thank you.
 

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