5. Class 11th Physics | Waves Motion | Propagation of a Progressive Wave Pulse | by Ashish Arora

let's discuss the propagation of a progressive
wave pulse , say we are given with a stretched string , along x axis , and say a wave pulse
is generated. at a time, t is equal to zero, which is having
, the shape, y is equal to f of x , this y is equal to f of x can be written as, the
equation of displacement of this wave pulse , which is travelling, say in the positive
x direction, at speed v , obviously at time t ,the wave will travel, a distance vt, and
it will keep the shape same . as we have studied that the phase of oscillating
particle will remain , unchanged s , as the wave propagates , or along with the wave propagation
phase also propagates , along with the shape and we can say the shape, is representing
the phase of particle at any instant . when a pulse is created at t equal to zero having,
the equation of displacement curve as y is equal to f of x .
and it is travelling at a speed v , then at time t it will be a position vt so if we talk
about , its shape after time t , we can write as after time t , equation of, displacement
curve . of the wave pulse , will be given as , here it be given as y is equal to f of
, x minus vt , because it has travelled a distance vt, so origin is vt distance displaced
behind, the wave pulse . so here we can say , the shape will remain
same, but the position coordinates of the pulse, are shifted by position vt , so if
it travelling in the positive direction of the x axis we can write its equation to be,
f of x minus vt , and if the wave is travelling in the negative direction of the x axis we
will write , it as, f of x plus vt, so be careful because some different types of numerical
we will discuss , which will be based on , the shape displacement curve of a wave pulse .

Author Since: Mar 11, 2019

  1. Sir, i also did not understand how origin is dispaced vt distance behind the wave pulse , please explain sir.

  2. Sir how did the expression f(x-vt) come? You said origin is vt distance behind the wave pulse… what does that mean? Please reply

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