# Pressure gauge submerged in a fluid column

1. Aug 15, 2011

### TyErd

1. The problem statement, all variables and given/known data
What reading will we see on a pressure gauge that is at the middle and bottom of a fluid column? and why

2. Relevant equations
P=pgh where p is density and P is pressure

3. The attempt at a solution
Well according to the equations as the gauge drop lower and lower it should decrease in pressure meaning before the gauge is dropped in it must have a greater than zero reading on the gauge and as it descends it reduces until it reaches zero, however that cannot be the case because pressure will increase when an object is submerged under water. Does it have something to do with buoyancy?

2. Aug 15, 2011

### SteamKing

Staff Emeritus
Try again Ty. The pressure is greater at the bottom of a fluid column. h is measured from the free surface of the fluid

3. Aug 15, 2011

### TyErd

so that means the readings will be opposite? so the gauge pressure at the top will be zero since h is zero?

4. Aug 15, 2011

### fleem

The equation gives the pressure at the bottom of a column, given the columns height. To use this equation, we simply define the gauge position as the bottom of the column. (We know that the fluid below the gauge does not affect its reading).