Concept:Water pressure in a dam increases with depth.
Explanation:The pressure exerted by water at a point is given by
P=hρg, where
h is the depth below the water surface.
As depth increases,
h increases, so the pressure
P becomes larger.
Therefore, the lower parts of the dam wall experience much greater pressure than the upper parts.
To withstand this greater pressure, the wall must be strongest and thickest near the bottom.
This prevents the dam from cracking or collapsing under the huge force of the water.
Answer:C. thickest at the bottom