Idea 5of 6Builds onOnly the fits surviveOne end open
Everything has a beat
Pluck a string hard, then gently. Same note?
Today you'll discover
- why a plucked string always settles on its own note
- what sets the rate a swing or a bottle prefers
- the name for the rate a thing swings at by itself
Think firstOne string, plucked hard and then gently
You pluck the string hard, then gently. Does the note change?
Decide first, then press Next. Watch what changes the rate and what only changes the size.
A one-metre string between two posts drawn in one loop. After a prediction, the loop is shown settling into one swing rate, then an air column is shown humming at its own rate, then a different string swings at a different rate. The last step asks what a longer playground swing does to its own rate.
See the whole ideathe big idea and the key word, in one place
The big idea
Every object swings at its own natural frequency when left alone.
Compare themHarder: louder, same rate. Longer or heavier: slower rate, however hard. The size of a swing and the rate of a swing are two different things.
Key word
- natural frequency
- a frequency at which an object vibrates on its own when disturbed; a string's harmonics are its natural frequencies
About this modelOnly wavelengths that fit the length survive; the rest cancel within a few reflections.
Only wavelengths that fit the length survive; the rest cancel within a few reflections.
Ready to use it?
- Say what sets a described object's natural frequency, and what changes it.