physics
posted by nick .
tank of water with L=6m, W=3m, H=4m.
1) Find the force on the bottom of the tank from water. (ignore atmosphere pressure).
2) If the door to the tank is 1.5m by 1.5m and it is 2.25m (center bottom)from the edge of the tank, what is the force on the door and the position of force from bottom of tank.
Please help me solve these questions!

wouldn't the force on the bottom equal the weight of the water?
WEight=volume*density*g
Now figure the pressure at the bottom: Pressure= weight/areabottom
Force on door= pressure*areadoor 
I though about the volume, this is what I have: F=72m^3x1000Km^3x9.8= 705600 KN/m^3
or 705.6 N/m^3. Is this right or no need to consider gravity? 
weight is volume*density*g
g is 9.8N/kg density is kg/m^3