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Question
The surface of water in a water tank on the top of a house is 4 m above the tap level. Find the pressure of water at the tap when the tap is closed. Is it necessary to specify that the tap is closed?
Solution
Given:
Height of the water tank above the tap level, h = 4 m
Acceleration due to gravity, g = 10 m/s2
Density of water, ρ = 103 kg/m3
When the tap is closed, the pressure of the water in the tap is
P = hρg
On substituting the respective values in the formula, we get:
P = 4 × 103 × 10
= 40,000 N/m2
It is necessary to specify that the tap is closed because if the tap is open, then the pressure gradually decreases as h decreases and also because the pressure in the tap is atmospheric.
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