Heavy and light: do they fall the same?
Galileo’s classic experiment, made interactive: a heavy and a light ball fall from the same height. Which lands first? Physics for kids 6+.
Press “Run”. Bodies move by the laws of physics: gravity, friction, elasticity.
What the experiment shows
A 10 kg ball and a 100 g ball are released together. In a vacuum (no air) they fall side by side and hit the ground at the same instant.
How to run it
- Before pressing “Run”, say out loud which ball you expect to land first.
- Run it and check your guess.
- Change the balls’ masses in the editor — the result stays the same.
Questions to discuss
- Why does a feather fall slower than a stone in real life?
- What would change on the Moon, where gravity is weaker?
The science
The pull of gravity on a body is proportional to its mass, but so is its inertia (resistance to changing speed). The two cancel, so every body accelerates equally: g ≈ 9.8 m/s². In real life air slows a feather down; our model has no air.
Try it at home
Hold a book and a sheet of paper, release them together — the book lands first. Now crumple the sheet into a tight ball and repeat. Discuss what changed (the shape, not the mass!).
What to change in the editor
- Add a third body — a square — and compare.
- Set gravity to 1.6 like on the Moon and see how much longer the fall takes.