Question

how many helium-filled balloons would it take to lift a person? assume the person has a mass of 73 kgkg and that each helium-filled balloon is spherical with a diameter of 30 cm cm .

Answer 1

Answer:

Mass = volume * density

tables show air = 1.293 g / L and He = .178 g / L

Each balloon would have a lifting power (using mass) of

(1.293 - .178) = 1.115 g / L = 1.115 kg / m^3

Note there are 1000 g in a kg and 1000 L in a m^3

V (balloon) = 4/3 pi .15^3 = .0141 m^3

Each balloon can lift .0141 m^3 * 1.115 kg/m^3 = .0158 kg

Or 63.4 balloons can lift 1 kg

To lift 75 kg requires 63.4 * 75 = 4760 balloons