A circular steel wire 2.00 m long must stretch no more than 0.25 cm wh...
Understanding the Problem
To determine the minimum diameter required for a circular steel wire, we must consider the relationship between tensile stress, strain, and Young's modulus.
Key Given Data:
- Length of wire (L) = 2.00 m
- Maximum stretch (ΔL) = 0.25 cm = 0.0025 m
- Tensile force (F) = 400 N
- Young's modulus for steel (E) = 2.00 × 10^11 N/m²
Formulas to Use:
1. Strain (ε): ε = ΔL / L
2. Stress (σ): σ = F / A
3. Young's Modulus (E): E = σ / ε
Calculating Strain:
- Strain (ε) = ΔL / L
- ε = 0.0025 m / 2.00 m = 0.00125
Calculating Stress:
Using Young's modulus, we can rearrange the formula to find stress:
- σ = E × ε
- σ = (2.00 × 10^11 N/m²) × (0.00125) = 2.5 × 10^8 N/m²
Finding the Required Area:
From the stress formula, we can find the cross-sectional area (A):
- A = F / σ
- A = 400 N / (2.5 × 10^8 N/m²) = 1.6 × 10^-6 m²
Calculating Diameter:
The area of a circle is given by A = (π/4) × d². Rearranging gives:
- d² = (4A) / π
- d = √((4 × 1.6 × 10^-6 m²) / π)
- d ≈ 0.0014 m = 1.4 mm
Conclusion:
The minimum diameter required for the wire is 1.4 mm, confirming option 'A' as the correct answer.