Question

Some miners wish to remove water from a mine shaft. A pipe is lowered to the water 90 m below, and a negative pressure is applied to raise the water. (a) Calculate the pressure needed to raise the water. (b) What is unreasonable about this pressure? (c) What is unreasonable about the premise?

Answer 1

Answer:

Explanation:

Given

Pipe is lowered to the water $h=90\ m$

Negative Pressure is applied to raise the water

Pressure is given by

$P=\rho gh$

where $P=pressure$

$\rho =Density$

$h=depth$

$P=10^3\times 9.8\times 90$

$P=8.82\times 10^{5}\ N/m^2\approx 8.82\ atm$

(b)8.82 atm is much lower than the vapor pressure of water

(c)The fact of applying a negative pressure of 8.74 below the vapor pressure of water