Simple stress, strain, elongation relationship question

AI Thread Summary
A user inquires about calculating normal stress, strain, and elongation for a circular steel bar under axial load. They correctly calculate normal stress as 159 MPa and normal strain as 795 x 10^-6 but struggle with elongation. The user initially misunderstands the conversion of strain to elongation, mistakenly expecting a different result. After clarification, they realize their error in metric conversion, acknowledging the need for more practice. The discussion highlights the importance of accurate unit conversion in engineering calculations.
Iclaudius
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Howdy ya'll,

a relatively simple question,

A circular bar 20mm in diameter and 1m long is subjected to an axial load of 50kN. Determine:

(i) The normal stress.
(ii) The normal strain.
(iii) The elongation.

Assume the material is steel with an Elastic Modulus of 200GPa.

ok so i got normal stress = 159 MPa, normal strain = 795*10^-6,
but here is my problem - solving for elongation why can i not just plug in the strain amount and solve for the change in length i.e strain * original length = change in length?
by the way elongation = 0.8mm which is not what i get using the aforementioned method.

(sorry for no math symbols)
Thanks in advance,
Claudius
 
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795 x 10-6 multiplied by 1 m is not approximately 0.8 mm?
 
oh snap, don't know what i was thinking lol, thanks for pointing out my oversight, guess i need more practice with the metric system :(
 

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