# Travelling Sounds

In this worksheet, students will consider questions about how the speed of sound through different materials can be investigated.

Key stage:  KS 2

Curriculum topic:   Sound

Curriculum subtopic:   How Sounds Travel

Difficulty level:

### QUESTION 1 of 10

How does sound get through objects, through the air, to your ears?

Well, sound is a form of energy that travels through materials by making PARTICLES in the materials vibrate.

When the particles are packed together tightly (makes the material DENSE), the sound waves travel easily and quickly.

In materials where the particles are spread far apart, for example, gases at room temperature, the sound waves do not travel as quickly.

Got that?  Maybe read it again and see if that helps you with the following questions.

First off, finish this sentence:

In science, SOUND is a form of.......

noise

music

energy

Find the missing word in this sentence.

Sound travels through materials by making _______ move.

particles

waves

air

Match up these materials with how their particles are arranged..

## Column B

solids
particles close together but 'free' to slide over ...
liquids
particles move freely to fill the space
gases
closely packed particles

Choose the correct order of these three materials from FASTEST to SLOWEST in terms of speed of sound, that is, how fast sound can travel through them.

There are five choices.  ONE is correct.

gas liquid solid

liquid gas solid

solid gas liquid

liquid solid gas

solid liquid gas

Here are three materials in a bottle of fizzy drink:

• carbon dioxide (the gas in lemonade)
• plastic

Have a think about this: which one of these materials would you expect sound to travel SLOWEST through?

carbon dioxide

plastic

Peter and Paulina want to show that SOUND WAVES travel better through solids than gases.

Which of the following objects do you think might they use to MODEL their science idea?

Go back and look at what they are trying to show before you pick your answer.

a mobile phone

a string phone

a loudspeaker

So, Peter and Paulina decide to investigate how sound travels through different materials using a string telephone.

They use clean yogurt pots as the receiver and mouthpiece.

They collect different materials to carry the sound waves between the pots.

Since they want to investigate how good the different materials are at carrying sound, which factor must they keep the same?

the stretchiness

the length

the strength

The students now speak down the string telephone and record their results in a table.

They record their results using these descriptions of the sounds they hear:

• very quiet
• quiet
• loud
• very loud
• clear
• unclear

Paulina does not think their results are very accurate.

Why do you think she reckons they're inaccurate?

the test was not fair

they could not measure the sound in the earpiece

Peter and Paulina want to repeat their investigation so that they have a SET OF MEASURES.

Which one of these factors could they CHANGE to improve their investigation?

material the pots are made of

size of the pots

the length of the string

Peter increases the length of the string until he cannot hear Paulina's voice. Their results show that sound travels furthest on NYLON STRING.

So, can you finish Peter's explanation for him?

The particles in nylon are..........

densely packed together

loosely packed together

strong

• Question 1

First off, finish this sentence:

In science, SOUND is a form of.......

energy
EDDIE SAYS
Yes. Whilst sound might seem like a noise or music to you, scientifically-speaking it's the vibration of particles of air that move in waves. The ones that reach your ears result in you hearing that sound. That movement of particles and of your eardrum show that sound is a form of energy - it can make things happen.
• Question 2

Find the missing word in this sentence.

Sound travels through materials by making _______ move.

particles
EDDIE SAYS
That might need some thought. Particles in materials move - vibrate - to pass on the sound energy. Particles are things like atoms and molecules. If you tap on the table, the particles of which the table is made transmit that tapping as vibrations which pass through the table and out into the air, so that your teacher can shout, "Who's that tapping?"!
• Question 3

Match up these materials with how their particles are arranged..

## Column B

solids
closely packed particles
liquids
particles close together but 'fre...
gases
particles move freely to fill the...
EDDIE SAYS
It's quite hard to picture, so a quick search for diagrams on the internet may help. Simply put, as you move from solid to liquid to gas, the particles of which they are made get further and further apart. That makes a big difference to how quickly they can transmit sounds.
• Question 4

Choose the correct order of these three materials from FASTEST to SLOWEST in terms of speed of sound, that is, how fast sound can travel through them.

There are five choices.  ONE is correct.

solid liquid gas
EDDIE SAYS
Remembering that as you move from solid to liquid to gas that the particles get further apart: how close the particles are together matches the speed of sound through the materials. Tightly packed (solid) = very fast transmission of sound. Quite close (liquid) = fast transmission of sound. Far apart (gas) = sound travels quite slowly. Hope that makes sense.
• Question 5

Here are three materials in a bottle of fizzy drink:

• carbon dioxide (the gas in lemonade)
• plastic

Have a think about this: which one of these materials would you expect sound to travel SLOWEST through?

carbon dioxide
EDDIE SAYS
Remember, carbon dioxide is a gas. The particles in carbon dioxide move and are not packed tightly together (not dense), so sound does not travel quickly through the gas. That's because it has to jump from CO2 molecule to CO2 molecule, just like you jumping from rock to rock as you cross a stream. It's a lot faster to run across the bridge!
• Question 6

Peter and Paulina want to show that SOUND WAVES travel better through solids than gases.

Which of the following objects do you think might they use to MODEL their science idea?

Go back and look at what they are trying to show before you pick your answer.

a string phone
EDDIE SAYS
So, a mobile phone and a loudspeaker send sound waves through the air, so that's not going to help them to show that solids conduct sound well. In fact, a string telephone is a very good way to model how sound waves travel through solids. You ought to have a go at making one yourself and trying it out: you'll need two old, clean cans (like baked beans cans that have been washed out) or a couple of yogurt pots, about 5m of string and something to bore a hole in the bottom of the can/pot (get some adult help with this - it's tricky). You make a hole in the bottom of each can/pot, thread the string through the holes and tie a knot to hold it there. Now you and a friend hold a can or pot each, walk away from each other until the string is tight, and one of you speak quietly into your can/pot while your friend put their can/pot to their ear, listening for what you are saying. This is designed to show how good sound is at travelling through solids (can or pot and string).
• Question 7

So, Peter and Paulina decide to investigate how sound travels through different materials using a string telephone.

They use clean yogurt pots as the receiver and mouthpiece.

They collect different materials to carry the sound waves between the pots.

Since they want to investigate how good the different materials are at carrying sound, which factor must they keep the same?

the length
EDDIE SAYS
Think about it: the students are investigating DIFFERENT MATERIALS which have different properties. They must keep the LENGTH the same so that it's a fair test. If they changed the length as well as the type of material, they wouldn't know which factor made the difference if their results changed.
• Question 8

The students now speak down the string telephone and record their results in a table.

They record their results using these descriptions of the sounds they hear:

• very quiet
• quiet
• loud
• very loud
• clear
• unclear

Paulina does not think their results are very accurate.

Why do you think she reckons they're inaccurate?

they could not measure the sound in the earpiece
EDDIE SAYS
The test was fair, but not very accurate because the students used their senses to describe the sounds but DID NOT MEASURE the sounds. What is a 'clear' sound to one person might be 'unclear' to another. We have to have a better, more measurable, way of investigating the materials' ability to carry sound.
• Question 9

Peter and Paulina want to repeat their investigation so that they have a SET OF MEASURES.

Which one of these factors could they CHANGE to improve their investigation?

the length of the string
EDDIE SAYS
If the students change the pots, they will be investigating different factors, NOT the material the string is made from! Measuring the length of the string when the sound can no longer be heard will give them a set of measures. That will really help their investigation and give them a chart of results and also be a repeatable experiment that their friends can try.
• Question 10

Peter increases the length of the string until he cannot hear Paulina's voice. Their results show that sound travels furthest on NYLON STRING.

So, can you finish Peter's explanation for him?

The particles in nylon are..........

densely packed together
EDDIE SAYS
Remember: sound vibrations travel easily through densely packed materials, like solids, because the vibrations can pass quickly from one particle to the next, to the next, and so on. Phew!
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