Question

The ratio of moment of inertia of the section about neutral axis to the extreme fibre distance from the neutral axis is

• A. Moment of inertia
• B. Radius of gyration
• C. Section modulus
• D. Polar moment of inertia

Hint:

Remember the key geometric properties and their roles:
- Area ($A$): Resists axial load.
- Moment of Inertia ($I$): Resists bending.
- Section Modulus ($Z = I/y_{max}$): A direct measure of bending strength.
- Polar Moment of Inertia ($J$): Resists torsion.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
Ratio I/y_max is called?

Step 2: Key Definition (Alternate):
Section modulus Z=I/y_max. Used in flexure formula: σ=M/Z. Measures bending strength.

Step 3: Detailed Explanation:
Radius of gyration k=√(I/A) for buckling. Polar moment J=I_x+I_y for torsion. Section modulus Z directly relates moment capacity to allowable stress.

Step 4: Final Answer:
Section modulus.