At 20°C, the minimum distance of a person from a sound reflecting surface to hear an echo is :

A. 12.2 m B. 17.2 m

C. 15.2 m D. 34.4 m

What type of waves are generated by SONAR device fixed to a fishing ship?

A. water waves B. radio waves

C. sound wavesD. infrared waves

We can distinguish between the musical sounds produced by different singers on the basis of the characteristic of sound called:

A. frequency B. timbre

C. pitch D. loudness

The drawing shoes a ship 800 m from a cliff. A gun is fired on the ship. After 5 seconds the people at the front of the ship hear the sound of the gun again.

(a) What is the name of this effect?

(b) What happens to the sound at the cliff?

(c) How far foes the sound travel in 5 seconds?

(d) Calculate the speed of sound.

Consider the following sound waves marked A, B, C and D:

(a) Which two waves represent sounds of the same loudness but different pitch?

(b) Which two waves represent sounds of the same frequency but different loudness?

(c) State whether all these sound waves have been produced by the same vibrating body or different vibrating bodies?

(d) Which vibrating body/bodies could have generated the sound waves shown here?