A school choir is practising in front of a vertical cliff on a calm morning when the air temperature is 20∘C. The choir master strikes a tuning fork and hears a clear echo from the cliff after 2.5s. Answer the following.
(a) Taking the speed of sound in air at 20∘C as 340m s−1, calculate the distance between the choir and the cliff.
(b) Later the air warms to 30∘C, increasing the speed of sound to 349m s−1. If the choir remains at the same place, find the new time gap between the sound and its echo.