When a pebble is tossed into a pond, a circular wave pulse propagates outward from the disturbance. if you are alert you will see a fine structure in the pulse consisting of surface ripples moving inward through the circular disturbance. explain this effect in terms of group and phase velocity if the phase velocity of the ripples if given by  s v p 2  , where s is the surface tension and  is the density of the liquid. (10 pts)