A $40-$cm$-$diameter circular gate $B$ has pressurized air to the left and water to the right. The gate is

hinged at the top.

a$)$ What is the hydrostatic force on the gate when $h=1m?(6$ points$)$

b$)$ At what water depth $h$ will the gate open? $(12$ points$)$

c$)$ If the air pressure is increased to $20$ kPa $,$ what would be the maximum value for $h$ without the

gate opening? $(8$ points$)$

for circle, $($:${}_t=9\mathrm{.}81k\frac{N}{m^3}$