09. Seeing with sound
You are provided with some text, artwork, a table and a graph. Use this information to answer the questions at the bottom of the page.
We know that sounds are produced when objects vibrate and that these sounds can travel at different speeds, depending on the medium that they are travelling through. Scientists know that sounds can be used for communication purposes and many believe that animals, such as dolphins, use sounds to ‘see’ things and to ‘talk’ to each other. The military and the medical profession use this knowledge for their own purposes. Ultrasound can be reflected when it travels from one material into another. If there is a big change in density of the material, say from more dense water into less dense air, then the wave will be reflected. This can be used to detect a number of things.
Table 1
This table show the percentage of sound that is reflected when ultrasound travels from one material into another.
Table 2
1 a Use the information provided in Table 2 to produce a bar chart of the speed of sound in different materials.
b Explain why plotting a bar chart is a good idea.
2 What is vibrating in each picture to produce the sounds?
3 Which of the pictures involve sound being used for communication?
4 Which of the pictures involve a reflection being necessary?
5 Explain why the diver will be unlikely to hear a person whistling on the shore.
6 In which pictures are the sound waves being used to:
a detect a dangerous situation b cause potential danger?
7 In which of the pictures will the sound be travelling:
a fastest b slowest?
8 Suggest why sound travels faster in sea water than in fresh water.
9 How might the bubbles affect the sound wave being sent from the submarine?
10 Which of the materials in the pictures is:
a most dense b least dense?
Explain your answer.
11 Which picture do you think shows the most useful use of sound? Why?
Can you...
> describe some examples of how sound is used
> analyse data from a variety of sources