JEE MAIN - Physics (2021 - 31st August Morning Shift - No. 10)
A uniform heavy rod of weight 10 kg ms$$-$$2, cross-sectional area 100 cm2 and length 20 cm is hanging from a fixed support. Young modulus of the material of the rod is 2 $$\times$$ 1011 Nm$$-$$2. Neglecting the lateral contraction, find the elongation of rod due to its own weight.
2 $$\times$$ 10$$-$$9 m
5 $$\times$$ 10$$-$$8 m
4 $$\times$$ 10$$-$$8 m
5 $$\times$$ 10$$-$$10 m
Explanation
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We know,
$$\Delta l = {{WL} \over {2AY}}$$
$$\Delta l = {{10 \times 1} \over {2 \times 5}} \times 100 \times {10^{ - 4}} \times 2 \times {10^{11}}$$
$$\Delta l = {1 \over 2} \times {10^{ - 9}} = 5 \times {10^{ - 10}}$$ m
Option (d)
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