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MHT CET 2021 (22 Sep, Shift 1) · Stationary Waves & Vibrating Strings

Stationary Waves & Vibrating Strings question from MHT CET 2021 (22 Sep, Shift 1)

Q78MHT CET 2021 · 22 SEP · SHIFT 1Medium

Stationary Waves & Vibrating Strings

A sonometer wire resonates with a given tuning fork forming standing waves with five antinodes between the two bridges when a mass of 9 kg9\text{ kg} is suspended from the wire. When this mass is replaced by a mass MM, the wire resonates with the same tuning fork forming three antinodes for the same positions of the bridges. The value of 'MM' is

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Answer: (d)

  1. Same fork and same bridge length: n=p2LTμn=\frac{p}{2L}\sqrt{\frac{T}{\mu}}, so pT=p\sqrt{T}= constant (pp = number of loops = antinodes).
  2. 59g=3Mg⇒M=55\sqrt{9g}=3\sqrt{Mg} \Rightarrow \sqrt{M}=5
  3. So the answer is (d) 25 kg25\text{ kg}.
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