Calculate the volume of the balloon filled with hydrogen gas, which will be sufficient to lift a load of 25 kg in air. Given that the densities of air and hydrogen are `0.00129g//c c` and `0.00009 g//c c` respectively.

Explanation

The weight of hydrogen in the balloon and load 25 kg will act vertically downwards while thrust of air vertically up. So the balloon will lift the weight if,
`"Th" ge "weight of hydrogen"+"load"`
or `Vrho_(air)g=Vrho_(H)g+Mg`
or `V(rho_(air)-rho_(H))=M`
or `(25xx10^(3)g)/((0.00129-0.00009))`
`=(25xx10^(7))/12`
or `V=2.083xx10^(7)"cc"`
`=20.83m^(3)`