Two wires as shown in the figure below, made of steel and have breaking stress of 12 × 10⁸ N/m². Area of cross-section of upper wire is 0.008 cm² and of lower wire is 0.004 cm². The maximum mass that can be added to pan without breaking any wire is ______ kg. (a) 56 (b) 38 (c) 96 (d) 5.6

Answer: (b). Upper wire holds (30 + 10 + m)g: (40 + m) × 10 ≤ 12 × 10⁸ × 8 × 10⁻⁷ = 960 N ⇒ m ≤ 56 kg. Lower wire holds (10 + m)g: (10 + m) × 10 ≤ 12 × 10⁸ × 4 × 10⁻⁷ = 480 N ⇒ m ≤ 38 kg. Both wires must survive, so take the smaller value. So the answer is (b) 38 kg.

Two wires as shown in the figure below, made of steel and have… | JEE Main 2026 (5 Apr, Shift 1)

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Thermal Stress & Breaking Stress

Two wires as shown in the figure below, made of steel and have breaking stress of $12 \times 10^{8}\text{ N/m}^2$ . Area of cross-section of upper wire is $0.008\text{ cm}^2$ and of lower wire is $0.004\text{ cm}^2$ . The maximum mass that can be added to pan without breaking any wire is ______ kg.

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Answer: (b)

Upper wire holds $(30 + 10 + m)g$ : $(40 + m) \times 10 \le 12 \times 10^8 \times 8 \times 10^{-7} = 960\text{ N} \Rightarrow m \le 56\text{ kg}$ .
Lower wire holds $(10 + m)g$ : $(10 + m) \times 10 \le 12 \times 10^8 \times 4 \times 10^{-7} = 480\text{ N} \Rightarrow m \le 38\text{ kg}$ .
Both wires must survive, so take the smaller value.
So the answer is (b) 38 kg.

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