Why Does a Transverse Wave Show Particle Movement Downwards?

[ibysaiyan]

Homework Statement

Now I know transverse waves have their particles oscillation 90 degree to their propagation.So for this question shouldn't the particle movement be "Vertically upwards at time 0.0s" for P.That's what I thought but the mark scheme I have been given states "downwards".
I don't quite get it. http://img141.imageshack.us/i/39942835.png/"
Any help will be appreciated. =]

Homework Equations

The Attempt at a Solution

 

[gneill]

Where would you locate particle P on the dotted curve "a short time later"?

 

[ibysaiyan]

Isn't the question asking for the orientation of the particle "P" on the bold line at 0.0s ?
Sorry I should have been more clearer in my OP.The question puzzling me is : 6 (b)(i)

 

[gneill]

Isn't the question asking for the orientation of the particle "P" on the bold line at 0.0s ?
Sorry I should have been more clearer in my OP.The question puzzling me is : 6 (b)(i)

The question is asking about the direction of travel of the particle at point P. The diagram depicts two snapshots of the wave separated by a short time interval.

So, where would you locate particle P on the dotted curve "a short time later"?

 

[ibysaiyan]

Oh dear I still don't get it...

 

[gneill]

Oh dear I still don't get it...

I'm not sure how to make it much clearer. Tell you what, why don't you explain, in your own words, what the two curves in the figure represent?