All the springs in fig. (a), (b) and (c) are identical, each having force constant K. Mass attached to each…

All the springs in fig. (a), (b) and (c) are identical, each having force constant K. Mass attached to each system is ' $m$ '. If $T_a, T_b$ and $T_c$ are the time periods of oscillations of the three systems respectively, then
  1. $\mathrm{T}_{\mathrm{a}}=\sqrt{2} \mathrm{~T}_{\mathrm{b}}$
  2. $T_a=\frac{T_c}{\sqrt{2}}$
  3. $\quad \mathrm{T}_{\mathrm{b}}=2 \mathrm{~T}_{\mathrm{a}}$
  4. $\quad T_b=2 T_c$

Solution

$\begin{aligned} T_a & =2 \pi \sqrt{\frac{m}{K}} \\ T_b & =2 \pi \sqrt{\frac{m}{\frac{K}{2}}} \\ \therefore \quad T_b & =2 \pi \sqrt{\frac{2 m}{K}}=\sqrt{2} T_a \Rightarrow T_a=\frac{T_b}{\sqrt{2}}...(i) \\ T_c & =2 \pi \sqrt{\frac{m}{2 K}}=\frac{T_a}{\sqrt{2}} \Rightarrow T_a=\sqrt{2} T_c ...(ii)\end{aligned}$
From (i) and (ii), $\frac{\mathrm{T}_{\mathrm{b}}}{\sqrt{2}}=\sqrt{2} \mathrm{~T}_{\mathrm{c}} \Rightarrow \mathrm{~T}_{\mathrm{b}}=2 \mathrm{~T}_{\mathrm{c}}$

Asked in: MHT CET 2024 (11 May Shift 2)

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