Idea 6of 9Builds onThe pattern moves, the stuff stays
Across or along
Push a slinky instead of shaking it. What travels?
Today you'll discover
- a wave with no crests
- which way the medium moves in each kind
- which kind sound is
Think firstA slinky pushed and pulled along its length
You push and pull one end of a slinky along its length. What travels down it?
Decide first, then press Next. Watch whether the marked coil moves across or along.
A row of tall thin ovals, the coils of a slinky, bunched in some places and spread in others, with one coil drawn filled. After a prediction, the frames advance: the marked coil shuttles left and right along the line while the bunched regions move to the right. The last step switches to air in a tube and asks what one particle does.
See the whole ideathe big idea and the key word, in one place
The big idea
Transverse: the medium moves across. Longitudinal: along.
Easy to get wrongSound is not air travelling to your ear. The air shuttles in place; the squeezes travel. A wind is not a sound.
Key words
- transverse
- a wave in which the medium moves at right angles to the direction the wave travels
- longitudinal
- a wave in which the medium moves back and forth along the direction the wave travels; compressions and rarefactions
About this modelThe coils shuttle along the line of travel; the pattern of squeezes moves on.
The coils shuttle along the line of travel; the pattern of squeezes moves on.
Ready to use it?
- Classify a described wave as transverse or longitudinal by what the medium does.