# Hydrostatic force with calculus

• Oct 12th 2008, 11:16 AM
fogel1497
Hydrostatic force with calculus
http://img91.imageshack.us/img91/4262/problemmz3.th.jpghttp://img91.imageshack.us/images/thpix.gif

That is my problem. I attempt to solve it by setting up an x-y axis with the origin at the center of the semicircle.

I then set up the following:

Hydrostatic Force =
INTEGRAL of: (width of a given strip)(height of a given strip)(density of water)(force gravity)(distance under water a given strip is)

Which with numbers looks like this:
INTEGRAL of: (sqrt(4-y^2))(dy)(1000)(9.8)(10-y)
I used trig substitution for the sqrt(4-y^2) and it simplifies to cos/cos, and go onto solve the integral with the bounds of 0-2. What am i doing wrong?
• Oct 12th 2008, 11:27 AM
galactus
Your set up looks OK. It is probably an integration mistake.

If you got 352800, then that is incorrect.

A word of advice: This is obviously a take home test, quiz, or something like that. In that event, folks will probably shy away from assisting much.
Just a thought...perhaps not.
• Oct 12th 2008, 11:48 AM
fogel1497
Its online homework, ill recheck my numbers. thanks.