Get premium membership and access revision papers with marking schemes, video lessons and live classes.

Processing. Please wait.

A mine-worker stands between two vertical cliffs 400m from the nearest cliff. The cliffs are x distance apart. Every time he strikes the rock once, he hears two echoes; the first one after 2.5 seconds, while the second follows 2 seconds later. From this information, calculate
i).The speed of the sound in air.
ii).The value of x.

Answer Text:
i).#Speed = (2d)/t = (2 times 400)/2.5 #= 320 m/s
ii).Distance = #s times t#
2(x – 400) = #320 times4.5#
= 1120 m