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JEE Main 2019 (12 Apr, Shift 2) · Inertia, First & Second Laws

Inertia, First & Second Laws question from JEE Main 2019 (12 Apr, Shift 2)

Q31JEE Main 2019 · 12 APR · SHIFT 2Medium

Inertia, First & Second Laws

A spring whose unstretched length is l has a force constant k. The spring is cut into two pieces of unstretched lengths l1 and l2 where, l1 = nl2 and n is an integer. The ratio k1/k2 of the corresponding force constant, k1 and k2 will be:

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Answer: (b)

  1. For pieces of the same spring, kl=constantkl = \text{constant}, so k∝1lk \propto \frac{1}{l}.
  2. k1k2=l2l1=l2nl2=1n\frac{k_1}{k_2} = \frac{l_2}{l_1} = \frac{l_2}{nl_2} = \frac{1}{n}
  3. So the answer is (b) 1n\frac{1}{n}.
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