1) The echo sounder of a ship emits a pulse of sound which is reflected back to the ship by a shoal of fish directly below the transmitter. The time between the transmission and reception of the pulse is 0.2 s. At what depth are the fish from the ship if the speed of sound in sea water is 1200 m/s?

2) Bees which are not carrying pollen fly with a flapping frequency of 440 Hz while those which are carrying pollen fly with a flapping frequency of 300 Hz.

The sound made by bees which are not carrying pollen

3) 2018 S4 EOY P1 Q14

The echo sounder of a ship emits a pulse of sound which is reflected back to the ship by a shoal of fish directly below the transmitter. The time between the transmission and reception of the pulse is 20 ms. At what depth are the fish from the ship if the speed of sound in sea water is 1400 m/s?

4) A point oscillator dipping into water in ripple tank has a period of 0.50 s. The resulting wave has a wavelength of 2.0 cm. What is the speed of the wave?

5) The depth of the seabed from position P to position Q is shown below.

Ultrasonic pulses are sent from a ship to the seabed as it travels from P to Q.

Which of the following graphs correctly represents the variation of the time interval between the emitted pulse and its echo from the seabed received by the ship as it moves from P to Q?