What is Liquid Pressure?
Liquid pressure is the pressure exerted by a liquid at any point inside the liquid. Any liquid in a container can be divided into multiple layers stacked upon one another. Liquid pressure arises due to force applied by these layers, at any given area inside the liquid.
How does Liquid Pressure Work?
Liquid pressure works in all directions. Let us understand this for the downward, upward, and sideward directions.
- Liquid pressure in downward direction – This is a result of gravitational force acting on layers of liquid. We often experience this downward push when we are swimming in water. This is nothing but liquid pressure acting in a downward
- Liquid pressure in upward direction – When we sink a plastic ball in water and release it, it rises back to the top. This is the upward pressure of liquid created by a force known as the Buoyant force.
- Liquid pressure in sideward direction – A liquid not only applies a downward or an upward pressure but also in the sideward direction or on the walls of its container. Let us understand this with the help of an
Consider a bottle filled with water. Make a small hole on the side of the bottle. We will observe that the water escapes out from that hole suggesting that something is pushing it outward. This is nothing but the liquid pressure acting in the sideward direction.
Liquid Pressure at Different Heights
If we make multiple holes at different heights in the bottle, we will observe that the water flowing out travels different distances, based on the height of that hole. In the image, the water from point A travels a lesser distance as compared to that from point B. This happens because the pressure at point B is more than that at A.
To understand why this happens, imagine that we have divided the water into multiple layers. We know that there is a downward force acting on each layer. But this downward force is not equal for every layer.
The top layer of water is applying a downward push on each of its below layers. The layer below the top layer also applies a downward push on the layer below it, but this push includes the force applied by the top layer as well. And similarly, for every layer below another layer, the force increases, thereby increasing the liquid pressure with an increase in depth.
Liquid Pressure at the Same Height
 We already know that with increasing height, the number of layers in a liquid increases thereby increasing the liquid pressure. But for the same height, the number of layers of liquid above them remains the same. This means that two points at the same height will experience the same liquid pressure.
Summary
| Liquid Pressure | Pressure exerted by a liquid at any point inside the liquid
Works in all directions Increases with height Same for the same height |
| Downward Liquid Pressure | Pressure applied by the weight of the layers of liquid in the container |
| Upward Liquid Pressure | Pressure created by the upward force of liquid known as the Buoyant force |
| Sideward Liquid Pressure | Pressure applied by liquid on the walls of its container |
 Did you know?
Liquid pressure exerted on the surface of an object causes upthrust. As the object placed in a liquid begins to sink, the liquid pressure and upthrust increases.
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