$(20$ pts$)$ A rectangular gate that is $3$ m wide $($in and out of the page$)$ is located in the vertical wall of a tank containing water as shown below. Air at atmospheric pressure is outside of the tank and the tank is open to the atmosphere. If the distance $l=1m$ to the frictionless horizontal shaft,

a$.(17$ pts$)$ Determine the moment, in N$-$m$,$ about the horizontal shaft. $($Ans: $M=+1,803,200N-m)$

b$.(3$ pts$)$ Will the gate open? $($Ans: No$)$

NOTE: Due to the stop on the lower wall the gate can only rotate in the clock$-$wise direction.