A simple spring has length ' $l$ ' and force constant ' $\mathrm{K}$ ', It is cut in to two springs of…

A simple spring has length ' $l$ ' and force constant ' $\mathrm{K}$ ', It is cut in to two springs of length ' $l_1$ ' and ' $l_2$ ' such that $l_1=\mathrm{n} l_2$ ($\mathrm{n}$ is an integer). The force constant of spring of length ' $l_1$ ' is
  1. $\mathrm{K}(1+\mathrm{n})$
  2. $\frac{\mathrm{K}(\mathrm{n}+1)}{\mathrm{n}}$
  3. $\mathrm{K}$
  4. $\frac{\mathrm{K}}{(\mathrm{n}+1)}$

Solution

Given $l_1=\mathrm{n} l_2$ $\therefore \quad \mathrm{k}_2=\mathrm{nk}_1$ Before cutting, the springs are connected in series, so $\therefore \quad \frac{1}{\mathrm{k}}=\frac{1}{\mathrm{k}_1}+\frac{1}{\mathrm{k}_2}$ $\frac{1}{\mathrm{~K}}=\frac{1}{\mathrm{k}_1}+\frac{1}{\mathrm{nk}_1}$ $\frac{1}{\mathrm{~K}}=\frac{\mathrm{n}+1}{\mathrm{nk}_1}$ $\therefore \quad k_1=\frac{K(n+1)}{n}$

Asked in: MHT CET 2023 (13 May Shift 2)

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