2. Objective
Pressure Variation in Fluid at Rest
Pressure Measurement
Mechanical Pressure Measuring Device
Hydrostatic Force on Plane Surface
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3. Pressure Variation in Fluid at Rest
p=po
h
A B
γ = specific weight
The pressure is the same at tall points along the line AB even with
irregular shape
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6. Hydrostatic Force on Plane Surface
Free Surface Free Surface
P=0 P=0
FR
h
P=γh
P=γh
Pressure on tank bottom Pressure on tank sides
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7. Hydrostatic Force on Plane Surface
x y
θ
FR hc A
Where
hc yc FR is the Resultant Force
FR hc is the vertical distance from the
fluid surface to the centroid of the
yR area and
A is the area
I xc Where
yR yc Ixc is the 2nd moment of the area
yc A
I xyc
xR xc = Zero in the uniform shape
yc A
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