Question

Why can i know the direction of propagates of wave by its equation y=Asin(omega t +- kx)??

My book write -kx mean the wave propagates from left to right
+kx mean the wave propagates from right to left

Please explain , Thanks

Answer 1

here.. i have given a line.. which is shown in red at t= 0.. imagine it is moving with speed v (example 1m/s) towards right.. how to write y as a function of t? ?.. just replace

x by (x-vt) and you ll see how it works..

i have redrawn the line after 1sec and shown the work..

Answer 2

thanks

Answer 3

by the way.. that is not my method.. it is how great WALTER LEWIN taught the MIT students.. i found that example amazing :D

Answer 4

hmmm...I learn alot from walter lewin great teaching skill too!

Answer 5

he does this in his 8.02 right before he starts teaching them about Electromagnetic waves

Answer 6

I'm sucks at wave and S.H.M , can you give a some fundamendal concept ?
Yes i know , but exam is coming no time for 8.02 , the 8.01 mechanic is great too

Answer 7

there are so many concepts..
pin point exactly which part you face a difficulty ... and maybe we all can help you

Answer 8

hmm....transverse wave equation , y=Asin(omega t +-kx)

i hardly understand concept of this equation,
is this derive from the uniform circular motion(S.H.M)?

Answer 9

yea well.. it is the basic equation of the travelling wave..

in S.H.M you study about one particle executing it.. a wave is lots of particles executing SHM .. the equation tells the amplitude of their vibration which becomes the amplitude of the wave itself.. angular frequency which again becomes the angular frequency of the wave itself.. and the last part kx, gives you the phase difference between any two particles sepearted by a distance of x

Answer 10

k is angular wave number.. which is 2pi/lambda..

if you chose a particle at a distance lambda from the origin then x = lambda.. then you know that you are choosing two particles which are a wavelength apart.. and must be in same phase..

then the the particle at origin will have y = a sin(wt) and at x you ll have y = asin(wt-kx)= a sin(wt-2pi)= asin(wt)

Answer 11

Thanks again : D