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JEE Main 2022 (25 Jul, Shift 1) · Young's Modulus & Elongation

Young's Modulus & Elongation question from JEE Main 2022 (25 Jul, Shift 1)

Q19JEE Main 2022 · 25 JUL · SHIFT 1Easy

Young's Modulus & Elongation

A wire of length LL and radius rr is clamped rigidly at one end. When the other end of the wire is pulled by a force FF, its length increases by 5 cm5\text{ cm}. Another wire of the same material of length 4L4L and radius 4r4r is pulled by a force 4F4F under same conditions. The increase in length of this wire is __________________ cm\text{cm}.

Numerical answer type. Work it out, then open the answer.

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Answer: 5

  1. Same material: ΔL∝FLr2\Delta L \propto \frac{FL}{r^2}
  2. ΔL′5=4F×4L(4r)2⋅r2FL=1616=1\frac{\Delta L'}{5} = \frac{4F \times 4L}{(4r)^2} \cdot \frac{r^2}{FL} = \frac{16}{16} = 1
  3. ΔL′=5 cm\Delta L' = 5\ \text{cm}
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