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Torsion formula terminology: identify J/R in the torsion equation Using the torsion relation T/J = τ/R = Gθ/L for circular shafts. State the standard name of the quantity J/R. Choose the correct term.

Difficulty: Easy

Shear modulus
Section modulus
Polar modulus (polar section modulus)
None of these

Correct Answer: Polar modulus (polar section modulus)

Explanation:

Concept/Formula
For circular shafts in torsion: T/J = τ/R = Gθ/L.Here, J is polar moment of inertia and R is outer radius. The ratio J/R is called the polar modulus (or polar section modulus), a geometric property indicating torsional strength.

Final Answer
Polar modulus (polar section modulus).

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