Rocket strums a rubber band stretched across an empty shoebox. Twang! The band blurs as it shakes.
"It is making music!" he says. "But how does the sound get to my ears?"
Raven presses a fingertip lightly on the band. The sound stops right away. "What do you notice when it stops moving?"
Nova leans close to the box. "Interesting," she says. "Sound seems to need a shake. Watch the band, then listen."
Sound is made when a force makes an object vibrate. Vibrate means move back and forth very quickly.
The vibrations pass energy through the air as sound waves. Then the waves reach your ears.
Inside your ear, the eardrum vibrates too. Your brain turns those signals into sounds you recognize.
Health scientists say the stronger the vibrations, the louder the sound.
Thunder is a sound made when lightning heats the air very quickly. The air expands fast and makes a sound wave.
You see lightning right away, but thunder takes about 5 seconds to travel 1 mile.
So count the seconds between the flash and the thunder. Then divide by 5 to get the miles.
| Seconds counted | Divide by 5 | Miles away |
|---|---|---|
| 5 | 5 divided by 5 | 1 mile |
| 15 | 15 divided by 5 | 3 miles |
| Statement | True or false? |
|---|---|
| Sound is made when something vibrates. | ? |
| When the rubber band stops moving, the sound keeps going. | ? |
| Stronger vibrations make a louder sound. | ? |
Remember the rule: about 5 seconds for each mile.
If Raven counts 20 seconds, she divides 20 by 5. The lightning is about 4 miles away.
A smaller count means the storm is closer.
If you can hear thunder at all, stay inside.
Nice work! Tomorrow you will see sound energy make rice jump.