An unknown gas has a density of 0.18 kg/m3, and air has a density of 1.275 kg/m3. If a balloon is filled with 0.129 m3 of helium,

Question

what is the maximum mass the balloon can have and still float?

Answer 1

Solution:

For the balloon to float, the density of the balloon has to be less than or equal to that of air that is

D_ball = D_air = 1.275 kg/m³

The volume of the balloon is V = 0.129 m³ , and D_ball = m / V

Then mass of the balloon m = D_ball * V = 1.275 kg/m³ * 0.129 m³ = 0.165 kg