# Physics

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An empty rubber balloon has a mass of 0.012kg. the balloon is filled with helium at 0 degrees celcius, 1 atm pressure, and a density of 0.179 kg/m3. the filled balloon has a radius of 0.5 m.

a)what is the magnitude of the buoyant force acting on the balloon?

b)what is the magnitude of the net force acting on the balloon?

• Physics -

(a) air density x volume
(If you want it in Newtons, also multiply by g)

(b)net force = balloon weight (empty) + helium weight - buoyant force
= balloon weight (empty) -(air density - helim density)*Volume

• Physics -

a) .009

• Physics -

The net force on balloon = the buoyant force (acts upward) minus the weight (downward)
The weight of helium filled balloon is:
volume of a sphere of radius = 0.5 m = 4/3πR³ = (4/3)(3.14)(0.5)³ = 0.523 m³
density of helium (at 0° and 1 atm) = 0.179 kg/m³
mass of helium in balloon = (0.179)(0.523) = 0.0937 kg
mass of rubber in balloon = 0.0120 kg
total mass of helium filled balloon = 0.0937 + 0.0120 = 0.1057 kg
total weight of helium filled balloon = (0.1057)(9.81) = 1.04 N

Accepting UR value of 6.62 for the buoyant force, the Net force is:
Net force acting on balloon = 6.62 (upward) - 1.04 (downward) = 5.58 N (upward) ANS

• Physics -

Lemme see what you're working on?