A ship’s horn sounds a steady 500 Hz tone while the ship moves directly toward a sheer cliff face at 10 m/s. The sound reflects from the cliff and returns to the ship as an echo. Taking the speed of sound in air to be 340 m/s, what frequency does a sailor on the ship hear for the echo?
a) 5.60×102Hz
b) 5.30×102Hz
c) 4.71×102Hz
d) 5.15×102Hz