Two blocks of masses 1 kg and 2 kg are connected by a metal wire over a smooth pulley. The breaking stress of the metal is (40/3π)×10⁶ N m⁻². What minimum wire radius will avoid breaking? Take g=10 m s⁻².
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Question

Two blocks of masses 1 kg and 2 kg are connected by a metal wire over a smooth pulley. The breaking stress of the metal is (40/3π)×10⁶ N m⁻². What minimum wire radius will avoid breaking? Take g=10 m s⁻².

Options

G1 Physics · Accepted Answer

Use stress σ=F/A, strain ε=ΔL/L and Young's modulus Y=σ/ε. For a uniform segment, ΔL=FL/(AY); for thermal restraint, thermal strain αΔT produces stress YαΔT. Evaluating the given data/statements gives B: 1 mm. Therefore the correct answer is B.