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MHT CET 2022 (11 Aug, Shift 2) · Organ Pipes & Resonance Tube

Organ Pipes & Resonance Tube question from MHT CET 2022 (11 Aug, Shift 2)

Q79MHT CET 2022 · 11 AUG · SHIFT 2Difficult

Organ Pipes & Resonance Tube

A hollow pipe of length 0.8 m0.8\text{ m} is closed at one end. At its open end, a 0.5 m0.5\text{ m} long uniform string is vibrating in its second harmonic and it resonates with the fundamental frequency of pipe. If the tension in the string is 50 N50\text{ N} and speed of sound in air is 320 m/s320\text{ m/s}, the mass of the string is

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Answer: (a)

  1. Pipe fundamental: f=v4L=3204×0.8=100 Hzf = \frac{v}{4L} = \frac{320}{4 \times 0.8} = 100\text{ Hz}
  2. String 2nd harmonic: f=22lTμ=10.550μf = \frac{2}{2l}\sqrt{\frac{T}{\mu}} = \frac{1}{0.5}\sqrt{\frac{50}{\mu}}
  3. 250μ=100⇒μ=0.02 kg/m2\sqrt{\frac{50}{\mu}} = 100 \Rightarrow \mu = 0.02\text{ kg/m}
  4. Mass =μl=0.02×0.5=0.01 kg=10 g= \mu l = 0.02 \times 0.5 = 0.01\text{ kg} = 10\text{ g}
  5. So the answer is (b) 10 g.
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