What is pressure at 100 feet under water?

Answer 1

First let's talk about units of pressure so that we can understand my answer later.

The unit for pressure is the pascal (Pa), equal to one newton per square meter (N/m2 or kg/m·s2)

A simple way to think about pressure is in this case is to realize that water has weight to it. Gravity is pulling the water towards the center of the earth, and the deeper you go the more water is above you and the greater the pull. Under gravitational constraints like this the pressure of any fluid can be calculated as the gravitational constant (g) multiplied times the density (ρ) multiplied times the height (h). In the case of water the calculation is relativly stright forward because it can be considered an incompressable fluid and therefore the density remains constant.

So to answer your question, the density of water is approxamtley 1000kg/m3 the height is 100 feet or 30.48 meeters ( to keep units consistant) and the gravitational constant on earth is approximatly 9.81 m/s2 slksj.

So we have to calculate it we take ρ*g*h which for this case is (1000kg/m3)*(9.81 m/s2)*(30.48m) which gives us 299008.8 kg/m·s2 or 299.0088 kPA.

We also have to take into account the pressure from gravity pulling on the air, this is not a straight forward calculation because air does not have a constant density (ρ) and must be integrated over. Luckly we know airpressure at sea level is 1atm=14.7psi = 101.325 kPa

So 299.0088 kPa + 101.325kPa = 400.334kPa

The short answer is 400.334 kPa, or about 3.951 atm, or 58.080 psi depending on what unit system you prefer.

Answer 2

Pressure = 10 * depth * density Density of water = 1000 kg/m3 depth = 3 feet = 0.9 meters Hence Pressure = 10 * 0.9 * 1000 Pressure due to water = 9 * 103Pa

Answer 3

About 37 pounds per square inch.

Answer 4

1470 psi