In music class, Raven claps along to a song. The claps ring out across the room.
Rocket claps too, louder and faster. After a minute he stops and rubs his palms. "My hands feel warm!"
Raven looks at her own hands. "Each clap is a tiny collision," she says. "What do you notice it makes besides motion?"
Nova bobs to the beat. "My hint," she says, "is to use your ears and your skin. Both are sensing energy."
In a collision, some energy usually transfers to the air around the objects.
That energy makes sound. It also warms the air a tiny bit.
So a crash sends energy three ways: into motion, into sound and into heat.
The heat is usually so small you cannot feel it from one bump. Many bumps add up, like Rocket's fast claps.
| Collision | Energy you might notice |
|---|---|
| Hands clapping | sound, a little warmth, hands bounce apart |
| A ball bouncing on the floor | sound, the ball moving back up |
| A door slamming shut | a bang of sound |
Sound is a vibration. A vibration is a quick back and forth shake.
When your hands clap, they shake the air around them. That shaking travels to your ears.
Sound carries energy from the collision out into the room.
That is how you can hear a crash from far away.
| Statement | True or false? |
|---|---|
| A collision can send energy into the air as sound. | ? |
| You can always feel heat from one tiny bump. | ? |
| A slamming door makes sound energy. | ? |
| Sound is a vibration. | ? |
Great listening today! Tomorrow you run your own crash test with marbles.