Calculate Force on Submarine Hatch due to Seawater Pressure

[dimpledur]

Homework Statement

A submarine is at a depth of 500 m under the water. The force on a circular hatch of 1.00 m in diameter due to the seawater (density = 1,025 kg/m3) pressure from outside the submarine is:

Homework Equations

F=PA
P2-P1=pgd

The Attempt at a Solution

F=(pgd+P1)A

where A = pi*r^2

When I plug in all the values, I cannot get the answer.

 

[dimpledur]

F=[(1025kg/m^3*9.8N/kg*500m)+1.013x10^5 Pa][pi*(0.5m)^2]
F=4.02x10^6 N

I have no clue where I am going wrong, in fact I thought this was an easy concept?

 

[dimpledur]

Did I mess up somewhere with the units?
Was I wrong to assume the pressure at the submarine would be P=pgd + 1.013x10&5 Pa?
I don't know...

 

[Stovebolt]

What is the answer supposed to be?

The only thing I can see would be that the question is asking for the force due to the pressure from the seawater, which might mean the water only, not the total pressure (which would include atmospheric pressure, as you did above).

 

[dimpledur]

That answer is not there either, though.

a. 2.45 × 106 N.
b. 3.95 × 106 N.
c. 4.94 × 106 N.
d. 5.50 × 106 N.
e. 6.34 × 106 N.

 

[dimpledur]

Nevermind figured it out thanks!