To determine the minimum gauge pressure needed in the water pipe leading into a building, we can use the concept of pressure and the height difference between the water pipe and the faucet on the twelfth floor.
We'll start by calculating the gauge pressure at the faucet on the twelfth floor using the height difference between the faucet and the water pipe.
The gauge pressure is given by the equation:
P = ρgh
Where:
P is the gauge pressure,
ρ is the density of the fluid (water in this case),
g is the acceleration due to gravity, and
h is the height difference.
We need to convert the height difference into the SI unit of meters, so 40m is already in the correct unit.
The density of water is approximately 1000 kg/m^3.
The acceleration due to gravity is approximately 9.8 m/s^2.
Plugging the values into the equation, we get:
P = (1000 kg/m^3) * (9.8 m/s^2) * (40 m)
P = 392,000 Pa
Therefore, the minimum gauge pressure needed in the water pipe leading into a building for water to come out of the faucet on the twelfth floor is 392,000 Pa (Pascals).