volume_mute
Fill in the blank to complete the rule governing floating objects in the atmosphere
publish date: 2026/05/20 22:17:29.870666 UTC
A rising hot-air balloon will stop ascending and hover at a constant altitude when its total downward weight becomes exactly equal to the upward (1) force exerted by the air.
Correct Answer
(1) buoyant
Explanation
A balloon continues to rise as long as the upward buoyant force is greater than its total weight. As it reaches thinned air layers where the buoyant force shrinks to perfectly match the balloon's weight, the net force drops to zero and the balloon enters vertical hovering equilibrium.
Reference
Basic Physics: A Self-Teaching Guide