Calculating Absolute and Gauge Pressure in a Gasoline-Filled Container

[JWHooper]

Homework Statement

Calculate the absolute and gauge pressure at the bottom of a 2.5 m deep container, if it is full of gasoline (density = 690 kg/m^3). Assume the container is open at the sea level.

Homework Equations

P = P_0 + Dhg

The Attempt at a Solution

P = (690 kg/m^3)(2.5m)(9.8 m/s^2) = (1.69 x 10^4 Pa)(1 kPa/10^3Pa) = 1.69 x 10 kPa (gauge pressure)
(1.69 x 10^4 Pa) + (1.01 x 10^5 Pa) = 1.18 x 10^5 Pa (absolute pressure)

My questions (important!):
1. Did I do these right?
2. Also, what is P_0 in the equation P = P_0 + Dhg?
3. gauge pressure + 14.7 lb/in^2 = absolute pressure ----> true or false? If not, please explain.

Thanks,

J.

 

[Mentz114]

2. Also, what is P_0 in the equation P = P_0 + Dhg?

I think you've answered your own question with the formula

P = P_0 + D.h.g

absolute pressure = atm. pressure + gauge pressure.

Interesting to speculate whether, if it was all underwater, the gauge pressure would be negative ?

 

[JWHooper]

I think you've answered your own question with the formula

P = P_0 + D.h.g

absolute pressure = atm. pressure + gauge pressure.

Interesting to speculate whether, if it was all underwater, the gauge pressure would be negative ?

So, P is the absolute pressure, P_0 is the atm. pressure, and Dhg is the gauge pressure?

 

[Mentz114]

Given that absolute pressure is measured in a surrounding vacuum, that is the case.

scienceworld.wolfram.com/physics/AbsolutePressure.html

 

[JWHooper]

Okay. Now, disregarding P_0, did I do the solution correctly?