A steel rod, 2 m in length. 40 mm in diameter, is subjected to a pull of 70 kN as shown in theTo what length should the bar be bored centrally from one end so that total extension will increase by 20% under the same force (the bore diameter is 25 mm and E is 2 × 105 N/mm2)?

• A. 0.46 m
• B. 0.55 m
• C. 0.87 m
• D. 0.62 m