A metal block of mass m is suspended from a rigid support through a metal wire of diameter 14 mm. The tensile stress is 7 × 10⁵ N m⁻². Find m in kg. [g = 9.8 m s⁻², π = 22/7]
Physics · Circular Motion
JEE Mains 6 April 2023 Shift 2 Evening Shift

Question

A metal block of mass m is suspended from a rigid support through a metal wire of diameter 14 mm. The tensile stress is 7 × 10⁵ N m⁻². Find m in kg. [g = 9.8 m s⁻², π = 22/7]

G1 Physics · Accepted Answer

Tensile stress is σ = F/A = mg/A The wire diameter is 14 mm, so radius is r = 7 mm = 7×10⁻³ m Cross-sectional area: A = πr² = (22/7)(7×10⁻³)² = 1.54×10⁻⁴ m² Given σ = 7×10⁵ N m⁻²: mg = σA = 7×10⁵ × 1.54×10⁻⁴ = 107.8 N Thus, m = 107.8/9.8 = 11 kg Final value: 11