Practice question

Given: A steel rod of radius 0.01 m and length 1.5 m is subjected to a tensile force producing a stress of 4 × 10⁷ N/m² . What is the force applied? (Take π approx 3.14 ) These values define the system as per NCERT data. Formula: Stress: Stress = F/A. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Area: A = π r² = 3.14 × (0.01)² = 3.14 × 10⁻⁴ m² . Force: F = Stress × A = 4 × 10⁷ × 3.14 × 10⁻⁴= 1.256 × 10⁴ N . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.