please solve and explain

Problem 5 ( 20 marks) Water (density 1000kg/m3 ) is contained by the massless, Lshaped gate shown, which has dimensions a=2m,b=2m,c= 3m, and is d=4m wide into the page. The air above the water and on the right side of the gate is at atmospheric pressure. The gate is held closed by a horizontal force, F, applied at the point shown. (a) Draw a free body diagram of the gate. (b) Calculate the minimum force, F, required to hold the gate shut