Why Everything Falls the Same Way
- Physics
- Ages 8–11 · Grades 3–5
- Hands-on experiment
What you’ll find out
- Objects of different mass fall at the same rate.
- Air resistance, not weight, is what slows light objects down.
- Shape changes how much air resistance an object meets.
No sign-up and no real names. In the lesson you check your understanding as you read, run the experiment yourself, and practise until it sticks.
Heavy and light land together
Hold a heavy ball in one hand and a light ball in the other, and drop them both at the same moment. Which lands first? Almost everyone says the heavy one. Try it, though, and they land together — you hear one thud rather than two. This surprises nearly everybody, and the reason is worth knowing. Gravity does pull harder on the heavier ball. But the heavier ball is also harder to get moving, by exactly the same amount, so the two effects cancel out perfectly.
So why does a feather lose?
But hold on. Drop a feather and a coin together and the coin wins easily. Does that mean the rule is wrong? No — something else has joined in. Air gets in the way of anything falling through it, and it gets in the way of a wide, light feather far more than a small, heavy coin. Astronauts have done this experiment inside a tube with the air pumped out, and with no air at all the feather and the coin fall side by side and land together. It was never about the weight. It was about the air.
Curriculum links: NGSS 5-PS2-1 · NGSS 3-PS2-1