Sound travels in a wavy (curly or curvy) way.
The way sounds travel through air, solids or liquids.
Now we know the way how we can hear sounds.
When something vibrates, sound waves are made and they move the air around them and make the air vibrate. These air vibrations enter our ears which we hear as sound.
1) If you ring a bell, the bell vibrates and makes sound waves. These sound waves make the air around them vibrate too and we can hear the bell is ringing.
2) Following picture shows us the way that we can hear the sound of a horn.
E.g. – You can clearly hear the rumble (a loud continuous noise) of a train when it travels near by, but when it travels further, little by little the sound decreases and cannot be heard clearly. That is why we cannot hear a distant sound.
Can you name one of the loudest sounds we hear? Thunder
Thunder is the loud sound made by lightning. Thunder sounds like an explosion. Lightning causes thunder.
Lightning is a huge electric spark.
|We can hear||We can see|
|Slower than the speed of light||Faster than the speed of sound|
The speed of light is faster than the speed of sound. Therefore in a storm we often see the thunder after we see the flash of lightning.
E.g. – 1) Sounds travel very well along metal pipes.
2) Sounds travel better through solid ground than through the air.
Sounds can be heard well underwater.
E.g. – 1) A diver can hear the engines of a boat before someone on the surface can.
2) Whales use sounds called, ‘songs’ to communicate with each other. These whale songs carry many hundreds of kilometres underwater.
A vacuum is a completely empty space. It has nothing, not even air in it.
No, they cannot. Sounds cannot travel through a completely empty space or a vacuum.
If there is a vacuum between a sound-making object and our ears, we won’t be able to hear the sound.
E.g. – 1) On the moon there is no air. You could talk to people right next to you and they wouldn’t be able to hear you.
2) If you want to talk to someone in space, you have to change sound vibrations to electrical or radio signals.
May 4, 2013