Question

A balloon filled with helium travels at a constant velocity in air (1.22 kg.m^3), The helium in the balloon has a volume 3.5 m^3 and density of 0.22 km/m^s. a. What is the magnitude of the buoyant force exerted by the air on the balloon? b. What is the mass of the balloon including the helium?

Answer 1

a)

V = Volume of the balloon = Volume of the air displaced = 3.5 m³

_air = density of the air = 1.22 kg/m³

magnitude of buoyant force on the balloon is given as

F_b = _air Vg

F_b = (1.22)(3.5)(9.8)

F_b = 41.85 N

b)

_He = density of helium = 0.22 kg/m³

V = volume = 3.5 m³

m = mass of balloon including the helium

we know that, force of buoyancy balaces the weight of the balloon including helium, hence

F_b = mg

41.85 = m (9.8)

m = 4.27 kg