When a balloon with a total mass of 400 kg rises to a certain height, it stays in the air. What is the buoyancy of the balloon If the volume of the balloon is 320 cubic meters, what is the air density at this height? (g = 10 N / kg)

When a balloon with a total mass of 400 kg rises to a certain height, it stays in the air. What is the buoyancy of the balloon If the volume of the balloon is 320 cubic meters, what is the air density at this height? (g = 10 N / kg)

Does a hot air balloon rise by the buoyancy of the air?
Is the density of the gas in the weather balloon less than that of the air?
Huang Gang champion, these are two options from a single multiple choice question. Your answer is both right. How can I choose?

Yes, because the density of the gas in the balloon is less than that of the air, the buoyancy of the balloon is greater than its gravity
Only when the density of the gas filled in the meteorological observation balloon is less than that of the air, can the balloon float. Maybe the density of the gas filled in the meteorological observation balloon is greater than that of the air. When it rises, it releases the gas downward and gains upward velocity through the action of recoil

A loaded hot-air balloon rises vertically at a constant speed under the buoyancy of 1000N in the air. If a 10kg object is added to the load, the balloon will descend at a constant speed

When the balloon is buoyant at 1000N in the air, it rises vertically at a constant speed, which indicates that the sum of downward gravity and air resistance is 1000N, that is, f floating = G + F. when the balloon descends, the air resistance becomes upward, that is, f floating + F = G + Mg, then G = 950N