Breaking Point for a Copper Wire

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SUMMARY

The maximum load that can be suspended from a copper wire of length 1.9 m and radius 1.2 mm without breaking is determined by its elastic limit of 2.9 x 108 Pa and tensile strength of 4.3 x 108 Pa. To calculate the breaking point, one must equate the stress in the wire to the elastic limit, using the formula for stress (σ = F/A), where F is the force in Newtons and A is the cross-sectional area. The area can be calculated using the radius of the wire, allowing for the determination of the maximum weight before permanent deformation occurs.

PREREQUISITES
  • Understanding of tensile stress and strain concepts
  • Knowledge of the relationship between stress, force, and area
  • Familiarity with the properties of materials, specifically copper
  • Basic proficiency in unit conversions, particularly Pascals to Newtons
NEXT STEPS
  • Calculate the cross-sectional area of a copper wire using the formula A = πr2
  • Learn how to derive stress from force and area in material science
  • Explore the concepts of elastic limit and ultimate tensile strength in materials
  • Investigate practical applications of tensile strength in engineering design
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Students in physics or engineering, material scientists, and professionals involved in structural design and analysis will benefit from this discussion.

Ike
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What is the maximum load that could be suspended from a copper wire of length 1.9 m and radius 1.2 mm without breaking the wire? Copper has an elastic limit of 2.9 x 10^8 Pa and a tensile strength of 4.3 x 10^8 Pa. Give your answer in Newtons (N).


Any thoughts? I'm completely lost.
 
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Well you may want to start by converting the Pascals to its other SI units (part of it is in Newtons...). That should make it a bit more apparent.
 
My main problem here is this...
When a wire is stretched, it will return to it's original length if the weight is removed. This is true, unless the elastic limit has been reached, in which case the wire will be permanently stretched. Before this point, the proportional limit is met, in which the tensile strain and the tensile stress are no longer proportional. Further beyond the elastic limit is the point of ultimate strength. I assume this is the same as tensile strength. Further beyond this point is the breaking point.

I have no idea how to derive the breaking point at all, nor how to find the maximum weight before that point for that matter.
 
Oh yes, and one Pascal is the same as one Newton per square meter.

1 Pa = 1 N/m^2
 
Since you are only given the elastic limit (yield point) the problem assumes that the onset of yielding will be the breaking point.

You should start looking at what the definition of stress is. If you set the stress in the wire equal to the elastic limit...
 

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