the image above shows an inverted U-tube with the open end, O of one limb below the level, W of water in the tank, in order that water should begin to flow from the tank it is is necessary that
Attached Figure / Diagram
A
The U-tube is completely filled with water and that P should be higher that W
B
P should be lower than O and W
C
P should be lower than W and O should reach the botton of the table
D
The U-tube is completely filled with water and that P should be lower that W
Verified Correct Answer: D.
Physical Principles & Numerical Solution
For water to begin flowing from the tank through an inverted U-tube with an open end at point P, the U-tube must be completely filled with water, and the pressure at point O inside the tube should be lower than the water level W in the tank.
Source: Myschool Past Questions Archive (Record #41636)