A girl stands on a straight road facing a high cliff. She claps her hands and hears the echo after 1.8 s. Assume the speed of sound in air to be 340 m/s.
(i) Calculate the distance between the girl and the cliff.
(ii) After walking 102 m closer to the cliff she repeats the clap. What time interval will she now measure between the clap and its echo? (Take the speed of sound to remain unchanged.)
(iii) State one practical application, other than distance measurement, that uses the same principle employed in parts (i) and (ii).