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## Main Question or Discussion Point

i am a chemical engineer but this is fluid mechanics stuff so i figured you physics geniuses would know this stuff

so to find the z component of force exerted by fluid on the surface of the sphere they find the normal force acting on a surface element of the sphere, integrated over the entire surface of the sphere. then dot it with unit vector in z direction. i am STUMPED as to how they found all the dot product in this integral. This is spherical coordinates

http://img716.imageshack.us/img716/6281/forcer.png [Broken]

here's the final result...

http://img685.imageshack.us/img685/5597/answern.png [Broken]

please let me know if you need any additional information

so to find the z component of force exerted by fluid on the surface of the sphere they find the normal force acting on a surface element of the sphere, integrated over the entire surface of the sphere. then dot it with unit vector in z direction. i am STUMPED as to how they found all the dot product in this integral. This is spherical coordinates

http://img716.imageshack.us/img716/6281/forcer.png [Broken]

here's the final result...

http://img685.imageshack.us/img685/5597/answern.png [Broken]

please let me know if you need any additional information

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