Question

The pressure of water in a water pipe when tap is closed and open respectively

Answer 1

The pressure of water in a water pipe when tap is closed increases and when tap is opened then it decreases.

we know that pressure in a pipe is given by the relation

P = force/area

hence pressure is inversely proportional to area

So when tap is closed the area decreases hence pressure increase.

Similarly when tap is opened the area increases hence the pressure decreases.

Answer 2

When the tap is Open,

Pressure is Increased because of the presence of the atmospheric pressure.

If the Pressure due to water is P, then the Total pressure in a open water pipe is P + P₀ where P₀ is the Atmospheric Pressure.

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When the tap is closed,

Pressure is decreased because there will be no atmospheric pressure.

If the Pressure due to water is P, then the Total pressure in a open water pipe is P only. It will not alter.

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Hope it helps.