JAMB - Physics (1983 - No. 40)
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
The U-tube is completely filled with water and that P should be higher that W
P should be lower than O and W
P should be lower than W and O should reach the botton of the table
The U-tube is completely filled with water and that P should be lower that W
Shpjegimi
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.