In the book 'Principles of Physics' by Resnick,Halliday and Jearl Walker,the opening para of derivation of wave speed from Newton's Second Law is such:
Let us consider a symmetrical pulse moving from left to right along a string of speed $v$. For convenience,we choose a reference frame in which the pulse remains stationary;i.e,we run along the pulse,keeping it constantly in view.In this frame,the string appears to move past us,from right to left with speed $v$
My confusion is :
If I am moving with the pulse,I should moving left to right with velocity $v$ wrt the reference for which pulse is moving left to right with velocity $v$.
So I should have zero speed wrt pulse and string both.
How can the string be moving right to left with speed $v$ if I am stationary to the pulse?
Are not the velocity of the pulse and velocity of the string are in the same direction and of same magnitude?