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JEE Main 2023 (30 Jan, Shift 2) · Young's Modulus & Elongation

Young's Modulus & Elongation question from JEE Main 2023 (30 Jan, Shift 2)

Q13JEE Main 2023 · 30 JAN · SHIFT 2Easy

Young's Modulus & Elongation

A force is applied to a steel wire 'A', rigidly clamped at one end. As a result elongation in the wire is 0.2 mm0.2\text{ mm}. If same force is applied to another steel wire ' BB ' of double the length and a diameter 2.42.4 times that of the wire ' AA ', the elongation in the wire ' BB ' will be (wires having uniform circular cross sections)

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Answer: (a)

  1. Same material and force: ΔL∝Ld2\Delta L \propto \frac{L}{d^2}
  2. ΔLB=0.2×2(2.4)2=0.45.76 mm\Delta L_B = 0.2 \times \frac{2}{(2.4)^2} = \frac{0.4}{5.76}\ \text{mm}
  3. ΔLB≈0.069 mm=6.9×10−2 mm\Delta L_B \approx 0.069\ \text{mm} = 6.9 \times 10^{-2}\ \text{mm}
  4. So the answer is (a).
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