# Standing waves.

## Homework Statement

A standing wave is set up on a stretched string as shown.
At which points will the osciallation be exactly in phase witht that at P?
At which points will the oscillation be exactly out of phase with that at P?
The points are on the horizontal line.
Q at 2
P at 5
R at 8
S at 12
T at 20
U at 22

## The Attempt at a Solution

Well, I am unsure on how to go about doing this quesiton. How do i calculate phase for this? Sorry if I'm sounding like I didn't not attempt. But I can't seem to understand how to calculate the phase difference here?
And also the particles would vibrate perpendicular up and down right? And how come its said that the for standing waves, within 2 adjacent N all particles have the same phase?

Is it because they particles move up and down and the fraction of cycle they have completed is the same thus the graph looks the same when its going up or comming down and the graph would look otherwise(distorted) if one completes half a cycle while other has completed the whole cycle?
Is it possible to clear my doubts using this question as an example. Appreciate any help given! Thank you very much.

Hmm. Ya. I have attached the picutre. And the points are located as where I have told in the above section. Thank you again. =)

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