４年生(Eネイティブ)理科
Natural Sciences and Technology Grade 4-B
Energy and Change
Chapter 2. Energy and sound p. 62-63
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音はエネルギーです。その伝搬の記載は前置詞の練習になりますね。
• Sound must travel through something.
• Your voice can travel through air.
• Your voice can travel through string.
• The tapping sounds can travel through a wall.
• We say that sound needs a medium to travel through.
• The medium your voice travels through is air
. • Sound travels through wood and bricks.
• Sound travels very well in solids
What happens when there is no medium? If you are able to watch the video of a bell ringing in a vacuum, then do so. Sound needs a medium to be able to travel. A vacuum is where there is no air or any other matter. So do you think you will be able to hear a bell ringing in a vacuum?
真空＝ vacuum は数えられる名詞です。上記でも A vacuumとなっていますね。
そしてテキストでは次に volume と pitchについて、わかりやすい説明が続いています。
Making sounds
Sometimes you need to speak softly when you whisper a secret to a friend.
But other times you need to shout loudly to your friend on the other side of the playing field!
Sounds have different volumes. Also, a mouse makes a very squeaky, high sound.
But a lion makes a low growl.
The sounds that these animals make have different pitches.
