# Water Pressure Homework Problem

• MMONISM
In summary, a person used an empty tube filled with sand to determine the depth they swam to in the ocean with a density of 1025 kg/m3. By using the hydrostatic equation, the person was able to calculate the depth to be 13.2 m, however this was incorrect due to forgetting to add in the surface pressure. With this correction, the accurate depth can be determined.
MMONISM

## Homework Statement

A person swim to certain depth in the ocean where the density of sea water is 1025 kg/m3. he does not have sophisticated equipment but he used an empty tube, the tube is L = 45.4 cm long and shaped like a cylinder. He wets the sides and then puts some sand in and shakes it around, coating the sides of the container. he was holding the tube vertically (the bottom is open the top is closed, allowing water to enter from the bottom) during the process. the person manages to wash away 10.9 cm of sand. How deep did the person dive?

PV = nRT
P = Pgh

## The Attempt at a Solution

As Pi = 1.01*10^5 Pa and Vi = A*L, as Pi Vi =Pf Vf (as the temperature of the tube doesn't change in ocean). and Vf = A*(0.454 - 0.109). Pf = (Pi*Vi)/Vf = (Pi*L)/(L - 0.109)
also Pf = P(density of sea water) gh, therefore h = (Pi*L)/((L - 0.109)*P(density)*g) = 13.2 m, but the answer is incorrect. could somebody help me please? Thanks in advance

In determining Pf from the hydrostatic equation, you forgot to add in the surface pressure.

Chet

CWatters
Chestermiller said:
In determining Pf from the hydrostatic equation, you forgot to add in the surface pressure.

Chet

Thank you very much!

## What is water pressure?

Water pressure is the force exerted by the weight of water in a specific area and is typically measured in pounds per square inch (psi).

## How do you calculate water pressure?

To calculate water pressure, you need to know the height of the water column (in feet) and the density of water (62.4 lbs/ft3). Multiply the height by the density and then divide by 2.31 to get the pressure in psi.

## What is the formula for water pressure?

The formula for water pressure is P = ρgh, where P is pressure, ρ is the density of water, g is the acceleration due to gravity (32.2 ft/s2), and h is the height of the water column.

## How does depth affect water pressure?

The deeper the water is, the greater the water pressure will be, due to the increasing weight of the water column. For every 10 feet of depth, water pressure increases by about 4.3 psi.

## What factors can affect water pressure?

Some factors that can affect water pressure include the depth of the water, the size of the container holding the water, the temperature of the water, and the elevation of the container.

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