Sound energy Vibrations All sounds are caused by
Sound energy
Vibrations - All sounds are caused by vibrations. - When you speak, the vocal cords in your throat vibrate. These vibrations transfer to the air particles around the vocal cords.
Vibrating Drum
Sound waves - Sound waves consist of a series of vibrating air particles. - Compression: air particles closer together than usual. - Rarefactions: air particles further apart than usual. - E. g A drum
Slinky sound waves - 1. Describe how the model is similar to real sound waves. - 2. Describe how the model is different from real sound waves.
Hearing sound - If enough energy is transferred through the vibrating air, the sound waves reach your eardrum and you hear sound. - The highness or lowness of a sound is called its pitch. - The faster an object vibrates, the higher the pitch of the sound it makes. E. g A short piece of string will vibrate faster than a long one so has a higher pitch.
Ruler - Hold a ruler over the edge of a table so that one end is firmly pushed down. Flick the overhanging end of the ruler. - Now move the ruler so that more of it is over the edge of the table and flick it again. - 1. How does the sound change as the vibrating part of the ruler is made shorter? Why?
Straws - Cut one straw into two so that one part is twice as long as the other part. - Alternating between the two pieces, place them against your bottom lip and blow gently across the opening. - 1. How does the sound change as the straws get shorter?
Beakers - Tap the side of a small beaker gently with a pen and listen to the sound. Do the same with a large beaker. - 1. How does the sound of the large beaker compare with the sound of the smaller beaker?
The need for air - Sound energy cannot travel through empty space. Why?
When sound meets a new substance • All materials transmit some sound, some better than others. That’s why you can sometimes hear conversations from the other side of a wall. • Sound is reflected from hard substances like the tiles in your bathroom. • Soft materials, like curtains and carpet, absorb much more sound than walls or tiles.
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