Ok got it! The "some distance from b" in my moment equation is = to Ycp. Which requires me to find the moment of inertia.
Ixx = (1/12)(8)(hcsc(60))3
Ycp = (Ixx(8)(hcsc(60))3sin(60))/((h/2)(8hcsc(60))
∑M = -150000+18339.6+287.8h2(Ycp) = 0 solve for h
∴ h = 10.59 ft
Thanks for your help guys!
Ok so the submerged area of the plate is going to be (8ft)*(the submerged length of A to B)...
If I create a triangle on the drawing and call the unknown submerged length 'x' I get x=h/sin(60).
Now I can plug that into the original equation I was asking about, hydrostatic force. So I now have...
Thinking more about it there would be a force due to the water acting on to the steel plate. I believe this force would also act in the center of the plate. I think this is what I am looking for to insert for the area in my original equation.
Right. You must mean the weight force of the steel plate which would act along the center of the plate.
So we would have...
(7.85)(62.3lb/ft3)(15ft)(8ft)(1/12ft)(7.5cos(60)) = 18339.6lb
Does that look right?
Homework Statement
Gate AB in Fig. P2.62 is 15 ft long and 8 ft wide into the paper and is hinged at B with a stop at A. The water is at 20°C. The gate is 1-in-thick steel, SG =7.85. Compute the water level h for which the gate will start to fail.
Homework Equations
F = δhcgA
Ycp =...