Question

The twisting moment of a circular shaft increases when:

• A. Rigidity modulus increases
• B. Polar moment of inertia decreases
• C. Length of the shaft increases
• D. Radius of the shaft increases

Answer 1

Answer:

A. Rigidity modulus increases

The twisting moment of a circular shaft increases when the rigidity modulus increases. This is because the torsion equation shows that T is directly proportional to G and J, and inversely proportional to L and R. Therefore, an increase in rigidity modulus will increase the twisting moment, while a decrease in polar moment of inertia, length, or radius of the shaft will decrease it.