The wall of a dam is broad at its base
Answers
The thickness of a wall dam is decided by the depth of water at that level.
Pressure of water is less at the topmost portion of the dam but as we go downwards the pressure exerted by water increases.
The maximum pressure exerted by water is towards the base of dam.
So, the dam walls at the base are broad.
Solution :-
The dam is kind of an organised pile of stuff. Piles are formed broad at the bottom and narrow at the top. Dams are designed to hold water back, and water is very heavy. It exerts much high pressure against the bottom and pressure of water against the top of a dam is substantial. Pressure of water increases as the depth increases. Wall of a dam is broad at its base so that it is strong enough to withstand the intense pressure of water.
There is an experiment explained.
Get a can or a large plastic bottle with a series of holes drilled in the side one above the other. Cover the holes with your fingers or a piece of sticky tape and then fill the container with water. Now remove the tape. The water gushes out but comes out faster from the holes that are nearer to the bottom where the depth is more. The reason behind this is the pressure of water is greater against the bottom of the container.