volume_mute
Why does a balloon filled with helium gas rise upward through the surrounding air atmosphere?
publish date: 2026/05/20 22:17:24.771626 UTC
volume_mute
Correct Answer
The weight of the displaced air is greater than the combined weight of the balloon envelope and the helium inside.
Explanation
Because helium gas is less dense than standard air, a balloon filled with helium weighs less than an equal volume of ambient air. Therefore, the upward buoyant force (the weight of the displaced air) exceeds the total downward gravitational weight of the balloon system, resulting in a net upward force.
Reference
Basic Physics: A Self-Teaching Guide