A circular shaft of diameter 30 mm is tested under torsion the gauge length of test specimen is 300 mm. A torque of 2kNm produces an angle twist of 1°. Calculate CJ.

• A. 0.432 × 10⁶ N/mm²
• B. 0.324 × 10⁶ N/mm²
• C. 0.46 × 10⁶ N/mm²
• D. 0.532 × 10⁶ N/mm²