Why do we use the distance to the centroid when finding the resultant force?

AI Thread Summary
The discussion centers on the use of the distance to the centroid (ybar) when calculating the resultant force on a plane surface under uniform pressure. It raises the question of why the centroid is used instead of the center of pressure, which is typically located below the centroid. Participants clarify that for uniform pressure, the center of pressure coincides with the centroid, making ybar the appropriate choice. The distinction between the distances to the centroid and center of pressure is acknowledged, but the uniformity of pressure simplifies the calculation. Ultimately, the uniform pressure condition justifies the use of the centroid in determining the resultant force.
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When find the resultant force on a plane surface under uniform pressure why do we use ybar, the distance to the centroid when the resultant force acts through the centre of pressure?

Shouldn't we use the distance to the centre of pressure?
 
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If the pressure is uniform, the center of pressure is at the centroid.
 
there's always two different values for the distance to the centre of pressure and to the centroid though?
 
Last edited:
For the second time, in your question the pressure is uniform.
 

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