A steel rod with 1250 mm² cross - sectional area and 3 m length is suddenly subjected to an axial pull of 50 KN. Determine the maximum stress induced in the rod.

Concept:

The maximum stress induced in a body due to a suddenly applied load is twice the stress induced when the same load is applied gradually.

Maximum stress due to sudden load (σ_max) = 2 × Stress due to the same gradual load

Maximum stress due to sudden load (σmax) = 2 × \(P\over A\)

Where P = load, and A = cross-sectional area.

Calculation:

Given

Cross-sectional area (A) = 1250 mm²

Length (L) = 3 m

Axial pull (P) = 50 kN or 50 × 10³ N

Maximum stress induced due to sudden load (σ_max) = 2 × \(({50× 10^3\over 1250})\) = 80 N/mm²

Maximum stress induced due to sudden load (σmax) = 80 N/mm²

Hence option (1) is correct.