The radius of pressure metre attached with a closed pipe is \( 4.5 \times 10^{4} \, \text{N}/\text{m}^{2} \). On opening the value, water starts flowing and the reading of pressure metre falls to \( 2.0 \times 10^{4} \, \text{N}/\text{m}^{2} \). The velocity of water is found to be \( \sqrt{V} \, \text{m}/\text{s} \). The value of V is ____________ .
