How Does Fluid Pressure Influence Pump Placement in Wells?

[gokuls]

Two questions:
1. Why is it that pressure exerted by fluids is not dependent on the amount of fluid around the point, only above?

2. Why is it that in deep wells, pump located underwater is better than a pump located on ground level?

 

[voko]

Two questions:
1. Why is it that pressure exerted by fluids is not dependent on the amount of fluid around the point, only above?

How does pressure arise in the first place?

2. Why is it that in deep wells, pump located underwater is better than a pump located on ground level?

Why would water go up to the pump above it?