Force on a submarine porthole at 500 m depth

[vipertongn]

Homework Statement

(a) Calculate the absolute pressure at an ocean depth of 500 m. Assume the density of sea water is 1024 kg/m3 and that the air above exerts a pressure of 101.3 kPa. --I got this one its 5118900 Pa or N/m

(b) At this depth, what force must the frame around a circular submarine porthole having a diameter of 28.0 cm exert to counterbalance the force exerted by the water?

Homework Equations

F=PA

The Attempt at a Solution

F= (5118900)(pi*.28^2)=1.26e6

Thing is this is wrong and I have no idea why. Can someone enlighten me?

 

[CFDFEAGURU]

Check your area of the circle equation. I think you are missing something there.

Thanks
Matt

 

[vipertongn]

OH gosh i put in the diameter rather than the radius thanks so much

 

[CFDFEAGURU]

Or you can keep the diameter. It is simply (pi*D^2)/4

Thanks
Matt