A circular opening of 'd' m diameter in a vertical side of tank is closed by disc of 'd' m diameter. Calculate the force on disc if head of water above horizontal diameter is 4 m :
1
\(\rho g\frac{\pi }{4}{d^2}\;\)
2
\(3\rho g\frac{\pi }{4}{d^2}\;\)
3
2ρgπd2
4
ρgπd2