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A standing wave formed by two waves travelling in opposite directions has transverse displacement y(x,t)=0.5 sin ((5π)/4x)cos(200π t), with x in metres and t in seconds. The speed of the travelling wave moving in the positive x-direction is

Asked in JEE Main Online 2017 · Nodes, antinodes and harmonics

Answer: (2) 160 m s⁻¹

Step-by-step solution

The component waves have the same ω and k as the standing wave: ω=200π rad s⁻¹ and k=(5π)/4 m⁻¹.

v=ω/k=200π×4/(5π)=160 m s⁻¹.

Why the other options are wrong

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