Question

Find the force F on a small dam in the shape of an inverted triangle, whose base(at water's surface) has length 4 meters and whose vertical height is 3 meters. (The dam is totally full, and the weight density of water is pg=9800 Newtons per cubic meter)

Answer 1

Hydrostatic pressure on an object submerged in a fluid is where is density of water and h is the depth of mass from the surface.

...............................................1) where h is depth from the surface

Force exerted =

Since A is not constant so we have to take a small deferential section dx at the depth of x from the surface, So

As shown in figure using properties of traingle we can easily find the width of dy slab

Now