The displacement $y($ in $\mathrm{cm})$ in case of a simple harmonic wave is given by $y=\frac{10}{\pi} \sin…

The displacement $y($ in $\mathrm{cm})$ in case of a simple harmonic wave is given by $y=\frac{10}{\pi} \sin \left(2000 \pi t-\frac{\pi x}{17}\right)$. The period and maximum velocity of the particles in the medium will respectively be
  1. $10^{-3} \mathrm{~s}, 330 \mathrm{~ms}^{-1}$
  2. ) $10^{-4} \mathrm{~s}, 20 \mathrm{~ms}^{-1}$
  3. $10^{-3} \mathrm{~s}, 200 \mathrm{~ms}^{-1}$
  4. $10^{-2} \mathrm{~s}, 2000 \mathrm{~ms}^{-1}$

Solution

Displacement equation in SHM is given as $ y=\frac{10}{\pi} \sin \left(2000 \pi t-\frac{\pi x}{17}\right) \mathrm{cm} $ Comparing with wave equation, $ y=a \sin (\omega t-k x) $ $ \begin{aligned} & \text { We get, } \quad a=\frac{10}{\pi} \mathrm{cm}=\frac{10}{\pi} \times 10^{-2} \mathrm{~m} \\ & \omega=2000 \pi \\ & \Rightarrow \quad \frac{2 \pi}{T}=2000 \pi \\ & \Rightarrow \quad T=0.001 \mathrm{~s} \Rightarrow T=10^{-3} \mathrm{~s} \\ & \end{aligned} $ Maximum velocity, $ \begin{aligned} v_{\max } & =\omega a=2000 \pi \times \frac{10}{\pi} \times 10^{-2} \\ & =2 \times 10^2=200 \mathrm{~ms}^{-1} \end{aligned} $

Asked in: AP EAMCET 2020 (22 Sep Shift 1)

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