Correct Option: B

Taking horizontal & vertical components of hydrostatic forces
F_H = ρ.g.h A_projected

= 1000 × 9.81 ×		H		× (H × 1)
		2

= 1000 × 9.81 ×		2		× (2 × 1)
		2

= 19.62 kN/m width.
F_v = weight of water displaced
= Mg
= ρvg = ρg. v

= ρ.g		π	R² × 1
		2a

= 1000 × 9.81 ×	π(1)²	× 1
	2

= 15.41 kN/m width

Location of centre of pressure, h' =	2	H
	3

=	2	× 2 = 1.33 m
	3

= 0.424 m
Moment about hinge,
⇒ –F_H × (h' - h) + F_v × x + F × 2/2 = 0
= – 19.62 × (1.33 – 1) + 15.41 × 0.424 + F × 1 = 0
∴ F = 0 kN