GATE Mechanical 2014 Set 2 | Question: 41

Question

A spherical balloon with a diameter of $10 m$, shown in the figure below is used for advertisements. The balloon is filled with helium ($R_{He}$ = $2.08 \: kJ/kg.K$) at ambient conditions of $15^\circ C$ 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 ($R_{air} = 0.289$ $kJ/kg.K$) is _______