Idea 6of 7Builds onHeavy and light fall togetherThe net arrow
Why the feather lags
In air, a feather lags a ball. Why?
Today you'll discover
- what the air does to a falling thing
- why the feather feels it more than the ball
- a fall that stops speeding up
Think firstIn air, the light ball falls behind
In air, the light ball lags the heavy one. Why?
Decide first, then press Next. Watch the gap between the two balls.
A large ball and a small ball released together, in air. After a prediction, the frames advance and the small ball falls behind, a bracket marking the growing gap. The last step pumps the air out and asks what a feather and a coin do in a vacuum.
See the whole ideathe big idea and the key word, in one place
The big idea
Air pushes back; a light thing feels it most.
Easy to get wrongWeight is not what slows the feather. Earth pulls each kilogram of it exactly as hard. The air's push back is just a bigger share of a tiny weight.
Key word
- air resistance
- the force the air exerts against an object moving through it; it grows with speed
About this modelWithout air, every mass falls the same way; the lag appears only when air pushes back.
Without air, every mass falls the same way; the lag appears only when air pushes back.
Ready to use it?
- Explain why a feather lags a coin in air and lands with it in a vacuum.