On Mohr’s circle for plane stress, what does the diameter of the circle represent?
- AThe average normal stress
- BThe maximum shear stress
- CThe difference between principal stressesCorrect
- DThe sum of principal stresses
Solution
Concept
Representation of diameter in Mohr's circle
Formula
NONE
Step-by-step solution
1. Mohr's circle provides a graphical transformation of plane stress components acting on inclined planes. 2. The radius of the circle represents the maximum shear stress within the plane. Answer: C
Explanation
On Mohr's circle, the two principal stresses lie at the extreme ends of the circle along the horizontal normal stress axis. The distance between these two principal stress points defines the diameter of the circle. Therefore, the diameter directly equals the difference between the maximum and minimum principal stresses, making option C correct.
Why the other options are wrong
A) The average normal stress corresponds to the center location of Mohr's circle on the normal stress axis. D) The sum of principal stresses equals twice the average normal stress, not the circle's diameter.
Shortcut
Mohr's circle radius = max shear stress, so diameter = difference between principal stresses (σ1 - σ2).
Common mistake
Confusing the diameter of Mohr's circle with its radius and selecting option B (maximum shear stress).
Correct answer: C) The difference between principal stresses