The Centre of Pressure (CP) and Centroid are distinct concepts in fluid mechanics, particularly when analyzing submerged surfaces. The Centroid is the geometric center of a shape, while the Centre of Pressure is the point where the resultant pressure force acts, which can differ due to pressure gradients. For submerged surfaces at angles, the pressure is not uniform, leading to a shift in the Centre of Pressure from the Centroid, as explained by Pascal's Law (P = ρgh). This distinction is crucial for accurate calculations in hydrostatics.
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RUber said:If pressure is applied evenly to a flat surface, then the center of pressure is the centroid. If a submerged surface is at an angle, then the pressure is not constant across the surface.
Likely RUber meant at an angle to the horizontal, which would include 90 degrees.SteamKing said:Even if the submerged surface is perfectly vertical, the centroid and the c.p. don't coincide because of the pressure gradient due to Pascal's Law where P = ρgh.