Question

The wall of a dam is broad at its base , give reason.

Answer 1

Dams are broad because to withstand the high force of water flowing. It also need to have less pressure on the land in which it stands as it is huge and heavy

Answer 2

The dam is kind of an organized pile of stuff. You know how piles always form, right? Broad at the bottom, smaller as you get toward the top. There’s a reason for that! Something on top of something else will generally fall off if there is not something else underneath it to keep it from slipping. That sort of interaction is going on between every piece of the pile, and it’s pretty much the same with a dam. At the beach, you may notice people making sand piles. If they keep trying to build the pile upwards, eventually the pile will collapse, and what you wind up with is a pile with a wide bottom and a narrow top.

Engineers can explain how stress between various particles in the pile makes this shape more or less inevitable. It’s a very stable shape for large piles like dams.

Also, of course, dams generally are designed to hold water back, and water is very heavy. It exerts a much higher pressure, however, as you go below the surface. The pressure of water against the top of a dam is substantial, but the pressure against the bottom of the dam is far greater. The dam has to be designed to take that pressure and not be near a point where it is at risk of failing.