Question

what force is required to stretch a steel wire of 1 cm^2 cross section to double its length? Young's modulus of steel is 2×10^11Nm^-2​

Answer 1

Answer:

Correct option: (A) 2 × 106 N Explanation: Y = {F / (A / strain)} hence F = Y × A × strain ∴ F = 2 × 1011 × 1 × 10–4 × strain F = 2 × 107 × strain (1) given 1.1 L1 = L2 (Δℓ / ℓ) = {(L2 – L1) / L1} = {(1.1 L1 – L1) / L1} = 0.1 (Δℓ / ℓ) = strain = 0.1 from (1), F = 2 × 107 × 0.1 F = 2 × 106 N