A spherical balloon with a diameter of 10m, shown in the figure below is used for advertisements. The balloon is filled with helium (RHe=2.08 kJ/kg.K) at ambient conditions of 150C and 100 kPa. Assuming no disturbances due to wind, the maximum allowable weight (in Newton) of balloon material and rope required to avoid the fall of the balloon (Rair = 0.28kJ/kg.K) is_______
