# Example question on pressure of liquids

In summary, the question is whether the horizontal extent or vertical depth of water behind a dam should be considered when designing it. One user suggests that the length and thickness of the dam wall should both be taken into account, while another user argues that depth is the determining factor for pressure. The discussion also mentions factors such as stress and strain of the wall under forces and the shape of the dam.
This question seemed a bit abstract to me, maybe some of you could come up with an answer with explanation?

When designing a dam should one consider the horizontal extent of the water behind the dam or the vertical depth of the water? Justify your answer.

Thanks.

Do you mean the length of the dam wall?

Hassan2 said:

Do you mean the length of the dam wall?

Yes, I mean the length of the dam wall as well as the thickness.

Yes, I mean the length of the dam wall as well as the thickness.

I'm not an expert in this field but according to my limited knowledge, the length of the wall does matter because the total force on the wall is proportional to area and the area is proportional to the wall length as well as to the water depth ( thickness). But a more detailed explanation is about stress and strain of the wall under the forces. Long dams are build oval-shaped or in other curved surfaces to resist the forces.

When designing a dam should one consider the horizontal extent of the water behind the dam …

i think that means, how far away the water extends from the dam

Depth determines pressure, not volume. This means that whether you're at the bottom of the ocean or at the bottom of a narrow well, as long as the water depth is the same, the pressure and force on you will also be the same.

tiny-tim said:

i think that means, how far away the water extends from the dam

This.

And to answer the original question with another, just think about it a bit. What affects the pressure, how deep you are or how much water you have around you?

## What is pressure?

Pressure is the force exerted on a surface per unit area. In the context of liquids, pressure refers to the force exerted by the weight of the liquid on the walls of its container.

## How is pressure of liquids measured?

The pressure of liquids is typically measured in units of pressure, such as Pascals (Pa) or pounds per square inch (psi). It can be measured using specialized instruments such as a manometer or a pressure gauge.

## What factors affect the pressure of liquids?

The pressure of liquids can be affected by several factors, including the depth of the liquid, the density of the liquid, and the acceleration due to gravity. The shape and size of the container can also impact the pressure of the liquid.

## How does pressure change with depth in a liquid?

In a stationary liquid, the pressure increases with depth. This is due to the weight of the liquid above pushing down on the lower layers. The deeper the liquid, the higher the pressure.

## What is Pascal's principle and how does it relate to pressure of liquids?

Pascal's principle states that a change in pressure applied to an enclosed fluid is transmitted equally throughout the fluid. This means that any change in pressure applied to a liquid will be transmitted to all parts of the liquid, regardless of its depth or shape. This principle is important in understanding the behavior of liquids under pressure.

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