Question

The volume of the balloon filled with hydrogen gas, which will be sufficient to lift a load of 24 kg in air is $({\rho }_{a}ir=0.00129gc{c}^{-1},{\rho }_H=0.00009gc{c}^{-1})$

• A. 20 m³
• B. 2 m³
• C. 0.5 m³
• D. 20 cm³

Answer 1

The correct option is A

20 m³

Upthrust = weight of $H_2$ + load

$V\rho mg=V\rho H_{2}g+mg\Rightarrow V=\frac{m}{(\rho air-\rho H_2)}=\frac{24\times {10}^3}{12\times {10}^{-4}}=2\times {10}^{-7}cc=20m^3$