Assertion: balloon's buoyancy | /r/HasProperty | controlled
Facets:
value: by heating the air
type: MANNER
Source sentences:
text: The buoyancy of a hot-air balloon is controlled by heating the air in the balloon or by changing the amount of ballast (extra weight).
text: The buoyancy of a gas balloon is controlled by changing the amount of gas in the balloon or the amount of ballast.