Final answer:
The steel wire subjected to a 25,000 N load will stretch by 2.5 cm under the given conditions, which corresponds to option (b).
Step-by-step explanation:
The student is asking about the stretching of a steel wire under a given load, a problem which can be solved using Hooke's Law and the concept of Young's modulus.
To determine the amount by which the wire stretches, we use the formula ΔL = (F × L) / (A × E), where ΔL is the change in length, F is the force applied, L is the original length, A is the cross-sectional area, and E is Young's modulus of the material. Substituting the given values: ΔL = (25,000 N × 20 m) / (1 cm² × 2×10¹¹ N/m²).
Converting the cross-sectional area to meters squared (1 cm² = 1×10¹´ m²) gives us: ΔL = (25,000 N × 20 m) / (1×10¹´ m² × 2×10¹¹ N/m²) = 2.5 cm, which is option (b).