the answer will be 83kn and 8.56m

just find the way to solve it please

Question # 2 Consider a heavy car submerged in water in a lake with a flat bottom. The driver's side door of the car is 1.1 m high and 0.9 m wide, and the top edge of the door is 8 m below the water surface. (a) Determine the net force acting on the door (normal to its surface) and the location of the pressure centre if the car is well-sealed and it contains air at atmospheric pressure (Answer 83 KN and 8.56 m) (b) The car is filled with water