Why does pressure change with elevation and depth?
Pressure changes with elevation and depth due to the weight of the fluid above a certain point. This concept is known as hydrostatic pressure.
When we move higher in the Earth's atmosphere or go deeper into a body of fluid, such as water, the amount of fluid above that point increases. The weight of this fluid creates pressure, which is exerted uniformly in all directions.
To understand why this happens, we need to look at the concept of gravity. Gravity pulls everything towards the center of the Earth. As a result, the force of gravity acting on a column of fluid becomes greater as we move deeper into the fluid or closer to the Earth's center.
The pressure exerted by a fluid at any given point is defined as the force per unit area acting on a surface. In the case of a fluid column, this means the weight of the fluid column divided by the area it is acting upon. Mathematically, pressure (P) is given by the equation P = ρgh, where ρ is the density of the fluid, g is the acceleration due to gravity, and h is the height or depth of the fluid column.
As we move higher in the atmosphere or deeper into a body of fluid, the height or depth (h) of the fluid column above the point increases. Since pressure is directly proportional to the height or depth, the pressure also increases.
For example, when you dive deep into a swimming pool, you may feel pressure on your ears. This is because the weight of the water above you is increasing, resulting in increased pressure. Similarly, when you ascend to higher altitudes, the height of the atmospheric column above you decreases, leading to decreased pressure.
In summary, pressure changes with elevation and depth because of the increasing weight of the fluid column above a certain point, caused by the force of gravity.