Dropped objects fall at the same rate regardless of weight when air resistance is removed.

The longer version

Gravity pulls on every piece of matter in proportion to its mass, so a heavier object feels a stronger force. Heavier objects also resist being accelerated more strongly, and the two effects cancel exactly. The result is that all objects gain speed at the same rate when nothing else interferes.

Air resistance is what usually breaks the tie. A flat, light object meets far more air relative to its weight, so it lags behind a compact heavy one. In a vacuum a feather and a stone fall together, which has been demonstrated with large evacuated chambers.

Where this entry sits

Everyday physics and chemistry hide small wonders in plain sight, from kitchen reactions to the light in the sky. These short facts explain matter, energy, electricity, magnets, sound, and the simple units we use to measure the world. The full list sits on the Science and Physics page, where every entry is listed in order.

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More From Science and Physics

Eight more entries

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Glass is often described as a slow-moving liquid, but it is really a solid with a disordered structure.

Helium balloons slowly shrink because the atoms are small enough to escape through the rubber.

Static shocks build up when two different materials rub together and then suddenly discharge.

Water boils at 100 degrees Celsius at sea level, but far lower high up a mountain.

Ice floats on liquid water because freezing makes it slightly less dense than the liquid.

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