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JAMB Physics 1983 Question 50

Question 50

Pressure

Fig. 11 above shows an inverted U-tube with the open end, O of one limb below the level, W, of water in a tank. In order that water should begin to flow from the tank it is necessary that

Diagram for this question
  1. A.the U-tube is completely filled with water and P should be higher than W.
  2. B.P should be lower than O and W
  3. C.P should be lower than W and O should reach to the bottom of the vessel
  4. D.The U-tube is completely filled with water and P should be lower than W
  5. E.the U-tube is completely filled with water and O should reach the bottom of the vessel.
Show the answer and explanation

Answer: D (The U-tube is completely filled with water and P should be lower than W)

Explanation

This is a siphon: it works only when the tube is full of water and its outlet P is below the water surface W in the tank.