In: Physics
How much force do you have to apply to hold a helium balloon of diameter 14cm and density ρballoon=0.1kg/m^3 stationary under normal atmospheric conditions. Assume the density of air ρair=1kg/m^3. Give a positive answer if you have to apply an upward force and a negative answer if you have to apply a downward force. Round your answer to 3 decimal places.
For convenience, we will work in SI units.
The volume of the balloon, assuming it to be spherical is
The buoyant force is equal to the weight of the displaced air minus the weight of the helium.
where is the acceleration due to gravity.
We need to apply the above mentioned force downwards.