Grade 11 · ⚛️ Physics · Mechanics · PHY-G11-M1.3
Galileo's race: stone vs paper
Drop a stone and a sheet of paper, then crumple the paper and race them again. Discover what really controls how fast things fall.
Why this matters
Galileo argued 400 years ago that, without air, a feather and a hammer fall at the same rate. Apollo 15 astronauts proved it on the Moon. On Earth, engineers designing the spillway of the Grand Renaissance Dam calculate falling water with g = 9.8 m/s².
Watch the demo
Video by BBC / Brian Cox
The science
g, the acceleration of gravity
Near Earth's surface, g ≈ 9.8 m/s². It points toward Earth's centre. In a vacuum, a feather and a hammer fall side by side because g doesn't depend on mass.
Air resistance
Air pushes against falling objects. It matters most for light objects with a large surface area. A parachute reaches terminal velocity when drag equals its weight.
You'll need
- A small stone or coin
- Two sheets of paper of equal size
Safety first
- Drop the stone onto soft ground or a mat, away from feet and anything breakable.
Step by step
0/4 doneWhat you should see
The flat paper drifts down slowly and lands long after the stone. The crumpled paper and the stone hit the ground at almost the same time.
Why it happens
Gravity gives every object the same acceleration g, whatever its mass. Flat paper has a large surface, so air resistance slows it a lot. Crumpling it reduces the surface area, so air resistance becomes small and it falls almost like the stone.
Didn't work? Try this
The stone always lands first, even against crumpled paper.
Crumple the paper tighter, and make sure you release both at exactly the same moment and height.
Still stuck? Ask the lab assistant
Check your understanding
1. Two balls of different mass are dropped from the same height in a vacuum. Which hits first?
2. What made the flat paper fall slowly?
Your lab notebook
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