A boy throws a pebble into a still pond. The pebble makes circular waves on the surface of the pond that have their crests 10 cm apart with an amplitude of 1.0 cm. The crests move outwards at a speed of 20 cms−1 . Draw graphs to show how the vertical displacement, x , of the surface of the water varies with
(a) distance, d , from the centre of the circular waves. (At d=0 , x=−1.0 cm )
(b) time, t . (At t=0 , x=−1.0 cm )