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Pressure in a Tank

  1. Mar 25, 2014 #1
    Hi all, I need some help with this question.


    The final answer is 32.7kN but I have no idea what I'm doing cause I'm so lost in this fluid mechanics class right now.

    I attempted to calculate the pressure on the plate.

    P = pgh
    P = 1000*9.8*2
    P = 19600 Pa

    Then I used F = P.A to get 78400N. I know this question has something to do with torque and resolving forces but I'm pretty sure I've already got it wrong. My lecturer provided me with this equation:

    y' = y + I_c/(y*A) and I_c is BH^3/12.

    Will I need to use this as well?

    Thanks in advance. :/
  2. jcsd
  3. Mar 26, 2014 #2
    Your value for P is not correct. I would calculate the value of P at different points to see why this is the case.
  4. Mar 26, 2014 #3
    Thank you for your reply. I've finally worked it out.

    Using that y' equation, I worked out the location off y' and then determined the amount of torque it placed on the hinge. That then equates to 2*F and after a simple rearragement, I solved the question as we just needed to make F the subject.

    The value of H is actually 1.5m as I was meant to be looking at the centroid.

    Thanks for the tip :)
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