[填空题]
A longitudinal wave is travelling in a medium from left to right. The diagram below is a snapshot of plane wave fronts of showing position of particles $X$ (center of compression) and $Y$ (center of rarefaction) in the medium at t=0 s.
1.Distinguish between a transverse wave and a longitudinal wave.
2.In the graph below, the solid line shows the variation of displacement $s$ of particle X with time, and the dotted line shows the variation of displacement of particle Y with time.
(1)Show that the angular frequency $ω$ of the oscillating particles in the medium is $3.9\,rad\,s^{−1}$.
(2)Calculate the speed of the wave in the medium.v= $cm\,s^{-1}$
3.(1)State the phase difference between particles X and Y.
(2)Determine the speed of particle Y when t=2.3 s.v= $mm\,s^{-1}$
