Which one of the following statements is correct regarding the Mohr’s circle of a plane Tensor ?
- Aσ is positive in tension and is plotted to the right of the origin. Compression is negative to the leftCorrect
- Bτ is plotted negatively if it rotates the stress block clockwise
- CAngles θ from one axis to another around the origin are in different direction
- DAny orthogonal set of axes are 90° to one another on Mohr’s circle
Solution
Concept
Sign conventions of Mohr’s circle
Step-by-step solution
1. Tension is taken positive and plotted to the right, compression to the left (true). 2. Orthogonal planes are 180° apart on the Mohr circle (so statement d is false). 3. The angle on the circle is twice the angle in the body and is measured in the same sense (so statement c is false).
Explanation
The horizontal axis carries normal stress with tension positive. Statement (d) should say 180°.
Why the other options are wrong
(b) depends on the convention adopted (shear is plotted positive when it turns the element clockwise in the common convention). (c) and (d) are wrong.
Shortcut
Planes at 90° in the body = 180° on the circle.
Common mistake
Choosing 90°.
Correct answer: A) σ is positive in tension and is plotted to the right of the origin. Compression is negative to the left