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MHT CET 2025 (19 Apr, Shift 1) · Stationary Waves & Vibrating Strings

Stationary Waves & Vibrating Strings question from MHT CET 2025 (19 Apr, Shift 1)

Q31MHT CET 2025 · 19 APR · SHIFT 1Medium

Stationary Waves & Vibrating Strings

A string of mass per unit length 0.1 kg m−10.1\text{ kg m}^{-1} has length 0.9 m. It is fixed at both ends and stretched such that it has a tension of 40 N. The string vibrates in three segments with amplitude 0.3 cm. The amplitude (maximum) of the particle velocity is (in m/s\text{m/s})

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Answer: (c)

  1. Wave speed v=T/μ=40/0.1=20 m/sv = \sqrt{T/\mu} = \sqrt{40/0.1} = 20\text{ m/s}.
  2. Three segments: 3λ2=0.9⇒λ=0.6 m3\dfrac{\lambda}{2} = 0.9 \Rightarrow \lambda = 0.6\text{ m}, so n=vλ=1003 Hzn = \dfrac{v}{\lambda} = \dfrac{100}{3}\text{ Hz}.
  3. ω=2πn=200π3 rad/s\omega = 2\pi n = \dfrac{200\pi}{3}\text{ rad/s}
  4. vmax=Aω=0.003×200π3=0.2π=π5 m/sv_{max} = A\omega = 0.003 \times \dfrac{200\pi}{3} = 0.2\pi = \dfrac{\pi}{5}\text{ m/s}
  5. So the answer is (c) π5\dfrac{\pi}{5}.
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