Balloons are often filled with helium gas because it weighs only about one-seventh of what air weighs under identical conditions. The buoyancy force, which can be expressed as (Fb=p-air g Vballon), will push the balloon upward. If the balloon has a diameter of 12 m and carries two people, 85 Kg each, determine the acceleration of the balloon when it is first released. Assume the density of air is p= 1.16 kg/m^3, and neglect the weight of the ropes and the cage.