All sounds are made when something vibrates, which means it moves backwards and forwards very quickly. When you pluck a guitar string you can see it shake. When you hit a drum, its skin vibrates. When you speak, your voice box in your throat vibrates: put your fingers on your neck and hum to feel it.
Vibrations can make things move too. Put rice on a drum and tap it: the rice jumps. Sound travels from the thing that vibrates, through the air, to our ears. A loud sound has big vibrations, and a quiet sound has small ones. Very loud sounds can damage our ears, so we use ear defenders near loud machines.
Worked example
Why do grains of rice jump on a drum when you hit it?
- Hitting the drum makes its skin vibrate.
- The vibrating skin pushes the rice up and down.
Answer:So the rice jumps, showing the drum is vibrating.
Key words
- sound
- what we hear
- vibrate
- move backwards and forwards quickly
- loud
- a strong sound with big vibrations
- ear defenders
- cover the ears to protect them from loud sounds
New questions every time.
NGSS-referenced: 1-PS4-1