1. A ship is sailing in dense fog and it could be close to dangerous cliffs. The captain switches on the fog horn. The horn sounds and the echo is heard 4 s later. The speed of sound in air is 340 m/s. a. Calculate the distance between the ship and the cliff.

b. Next time the fog horn sounds it takes 3.5 s for the echo to be heard. State whether the ship is further from, nearer to or at the same distance from the cliff.

2. A person is 30 m away from a reflecting surface. He claps his hands and hears the echo. If the speed of sound in air is 340 m/s, how long does it take from the time the person claps his hands to hearing the echo?

3. A spectator saw a cricketer hit the ball and heard the sound a short while later. The speed of sound in air is 340 m/s and the spectator was 80 m away from the batsman. what was the approximate time difference between the spectator seeing and hearing the ball being struck?

4. In an experiment to measure the speed of sound in air, a student blew a short blast on a whistle and raised an arm at the same time. An observer 500 m away heard the whistle blast 1.5 s after seeing the arm raised.

a. Explain why the whistle blast was heard by the observer after the arm was raised.

b. Use the data to calculate the speed of sound in air.